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Essential Statistics
If X is a binomial random variable with parameters 10 and 0.3, then P(X = 3) = _____.
- Select one:
- a. 0.73
- b. 0.27
- c. 0.39
- d. 0.35
- e. 0.65
A school district is assumed to have 8,000 5th graders. The average weight of a 5th grader is 75 pounds, with a standard deviation of 20 pounds. If a random sample of 50 students is drawn, find the probability that the average weight of a student from the drawn sample will be less than 70 pounds.
- Select one:
- a. 1.07
- b. 0.00
- c. 1.00
- d. 0.038
- e. 0.962
The test statistic for large sample hypothesis tests concerning a single population proportion follows:
- Select one:
- a. normal distribution
- b. standard normal distribution
- c. Student’s t-distribution with n – 1 degrees of freedom
- d. Student’s t-distribution with n – 2 degrees of freedom
- e. exponential distribution
The proportion of a population with a characteristic of interest is p = 0.35. Calculate the mean of the sample proportion obtained from random samples of size 900.
- Select one:
- a. 0.004
- b. 0.12
- c. 0.012
- d. 0.35
- e. 3.5
A numerical quantity that is generated by a random experiment is called a(n) _____.
- Select one:
- a. random variable
- b. observable variable
- c. numerical variable
- d. expected variable
- e. experimental variable
A random sample of size 144 is taken from a population in which the proportion with the characteristic of interest is p = 0.56. Find the mean.
- Select one:
- a. 0.56
- b. 0.00
- c. 1.00
- d. 0.17
- e. 0.83
Find the probability, P(-1.11 < Z < 2.12) for a standard normal variable Z.
- Select one:
- a. 0.1335
- b. 0.8438
- c. 0.9830
- d. 0.8495
- e. 0.1505
A(n) _____ is a number that summarizes some aspect of the sample data.
- Select one:
- a. sample
- b. population
- c. residual
- d. parameter
- e. statistic
For a standard normal variable Z, which of the following z values satisfies the expression: P(Z = z) = 0.5636.
- Select one:
- a. -0.16
- b. -0.14
- c. 0.14
- d. 0.16
- e. 0.84
For the sample space S = {j, k, l, m, n}, identify the complement of A = {k, m}.
- Select one:
- a. {j, l}
- b. {j, k, l, m, n}
- c. {l, n}
- d. {j, l, n}
- e. {j, k, l, n}
The subset of a sample space is called a(n) _____.
- Select one:
- a. sample set
- b. space
- c. event
- d. sample subset
- e. event space
Find the mean of a binomial random variable with parameters n = 5 and p = 0.5.
- Select one:
- a. 0.50
- b. 1.25
- c. 2.50
- d. 12.5
- e. 0.10
Construct a sample space for the experiment of tossing two distinguishable coins (h for heads and t for tails).
- Select one:
- a. S = {hh, tt, ht, th}
- b. S = {h, t}
- c. S = {hh, tt, th}
- d. S = {h, h, t, t}
- e. S = {tt, hh}
Let us consider a dice to be rolled eight times. What is the probability that the face with two spots comes up exactly twice?
- Select one:
- a. 0.17
- b. 0.03
- c. 0.24
- d. 0.26
- e. 0.53
For the data set {1.5, 2.3, 1.7, 3.6, 2.9, 4.2, 3.3} find the second quartile, Q2.
- Select one:
- a. 2.3
- b. 2.9
- c. 2.6
- d. 1.7
- e. 3.6
A journalist plans to interview an equal number of people in two cities to compare the proportions in each city that favor the proposal of privatization of government-controlled state public transportation. Let p1 and p2 be the true proportions of people of the two cities who are in favor of the proposal. Suppose it is desired to find a 99.9% confidence interval for estimating p1–p2 to within 0.08. Estimate the minimum equal number of people of each city that must be sampled to meet these criteria.
- Select one:
- a. 257
- b. 1693
- c. 846
- d. 258
- e. 847
A retailer wishes to estimate the difference in the average sales of a soft drink sold in two kinds of flavors, at 98% confidence and to within six dollars. Estimate the minimum equal sample sizes necessary if it is known that the standard deviations of the sales on these two flavors of the soft drink last week was $11.50 and $14.20.
- Select one:
- a. 22
- b. 3
- c. 51
- d. 4
- e. 50
Kendra orders five handmade mugs from an online site that claims that it averages only five damaged mugs for every 50,000 mugs it produces. What is the probability that Kendra’s order contains one or more defective pieces?
- Select one:
- a. 0.0001
- b. 0.9999
- c. 0.0005
- d. 0.9996
- e. 0.0004
A pair of balanced dice are rolled. What is the probability of not rolling doubles?
- Select one:
- a. 1/36
- b. 1/6
- c. 1/18
- d. 1/12
- e. 5/6
An investor expects a return of 4% with a standard deviation of 6% on his savings. Use the empirical rule to find the probability of earning a return greater than 15% if the investment returns are normally distributed.
- Select one:
- a. 0.14%
- b. 3.36%
- c. 2.28%
- d. 0.28%
- e. 95.44%
A fair die is rolled. What is the probability that the number rolled is seven?
- Select one:
- a. 0
- b. 1
- c. 1/2
- d. 1/4
- e. 3/4
Assume that IQ scores follow a bell-shaped distribution with a mean of 100 and a standard deviation of 16. Use the empirical rule to find the percentage of people who scores between 52 and 148.
- Select one:
- a. 68
- b. 95
- c. 97.47
- d. 98.26
- e. 99.7
The deterministic part of the simple linear regression equation describes:
- Select one:
- a. why the actual observed values of y are not exactly on but fluctuate near a line.
- b. the magnitude of the noise in the data.
- c. the three parameters in the model.
- d. the trend in y as x increases.
- e. the expected change in y brought about by a unit increase in x.
The heights of male high school students are measured. The average height is found to be 68 inches with a standard deviation of 2 inches. The distribution is approximately normal. If we draw a random sample of 16 boys from the school, then the standard deviation of the sample mean is:
- Select one:
- a. 70
- b. 0.5
- c. 1
- d. 0.25
- e. 2.5
For a sample space S = {q, r, s, t}, suppose two events are identified as A = {q, t} and B = {r, s}. Also, P(q) and P(r) are 0.3 and 0.5 respectively and P(t) = 0.2. Calculate the P(A).
- Select one:
- a. 0.8
- b. 0.3
- c. 0.5
- d. 0.2
- e. 0.0
A women’s softball team plays soccer 2, 3, or 1 days a week. The probability that they play 2 days is 0.3, the probability that they play 3 days is 0.2, and the probability that they play 1 day is 0.5. Determine the average days per week that the team plays softball.
- Select one:
- a. 0.33
- b. 1.0
- c. 1.1
- d. 0.8
- e. 1.7
The heights of male students at a high school are measured. The average height is found to be 68 inches with a standard deviation of 2 inches. The distribution is approximately normal. If we draw a random sample of 16 boys from the school, what is the probability that the average height of these 16 boys is 71 inches or taller?
- Select one:
- a. 0.50
- b. 0.07
- c. 0.93
- d. 0.00
- e. 1.00
Sean orders 20 pairs of gloves from an online clothing manufacturer. The site claims that it averages only 12 damaged pair of gloves for every 45,000 it produces. What is the probability that there are no perfect pieces in his order?
- Select one:
- a. 1.000
- b. 0.000
- c. 0.994
- d. 0.860
- e. 0.140
A random sample of 8 students are selected from a class of 45 and their heights (in inches) were recorded as follows: {62.3, 68, 64, 66.1, 65.4, 61.8, 65.2, 68.6}. Compute the sample median.
- Select one:
- a. 63.43
- b. 66.93
- c. 68.21
- d. 65.18
- e. 64.57
A(n) _____ is any specific collection of objects of interest.
- Select one:
- a. population
- b. parameter
- c. statistic
- d. estimate
- e. estimator
Consider a sample space S = {l, m, n, o}. Suppose P(l) and P(m) are each 0.3 and P(n) = 0.2. Find P(o).
- Select one:
- a. 0.0
- b. 0.1
- c. 0.3
- d. 0.2
- e. 1.0
The _____ of a continuous random variable X is an assignment of probabilities to intervals of decimal numbers using a function f(x), called a density function.
- Select one:
- a. probability distribution
- b. probability mass function
- c. density
- d. probability-generating function
- e. joint mass function
For a standard normal variable Z, which of the following z values satisfies the expression: P(Z = z) = 0.5636.
- Select one:
- a. -0.16
- b. -0.14
- c. 0.14
- d. 0.16
- e. 0.84
A(n) _____ is a number that summarizes some aspect of the population as a whole.
- Select one:
- a. sample
- b. population
- c. statistic
- d. parameter
- e. estimator
A researcher wants to determine the average income of the people of Omaha, Nebraska. He found that there are 385,600 employed people in the state. A group of 1,200 people are selected randomly to ascertain the income of each of those individuals. He finds that the average income of those 1,200 numbers to be $42,827. Identify the parameter in this context.
- Select one:
- a. 385,600 employed people in Omaha
- b. 1,200 people selected for the study
- c. Average income of $42,827
- d. 385,600 – 1,200 constitute the population
- e. 385,600 + 1,200 constitute the population
The goodness-of-fit χ² test is always:
- Select one:
- a. right-tailed, since deviation from the assumed probability distribution corresponds to small values of χ².
- b. left-tailed, since deviation from the assumed probability distribution corresponds to large values of χ².
- c. two-tailed, since deviation from the assumed probability distribution corresponds to large values of χ².
- d. right-tailed, since deviation from the assumed probability distribution corresponds to large values of χ².
- e. left-tailed, since deviation from the assumed probability distribution corresponds to small values of χ².
Consider a random experiment of rolling a fair die. List the outcomes for the event of rolling a number greater than two.
- Select one:
- a. E = {2, 3, 4, 5, 6}
- b. E = {3, 4, 5, 6}
- c. E = {4, 5, 6}
- d. E = {5, 6}
- e. E = {3}
In a class of students, which of the following refers to quantitative data?
- Select one:
- a. Data on students’ favorite color
- b. Data on students’ score on a History test
- c. Data on whether students own at least one pet
- d. Data on students’ mode of transportation to school
- e. Data on each child’s gender
A random sample of 5 students is selected from a class of 35, and their heights (in inches) were recorded as follows: 63, 66.5, 62, 64.2, 70.8. Find the sample mean.
- Select one:
- a. 64.0
- b. 67.1
- c. 65.3
- d. 68.2
- e. 69.8
Identify the characteristic of the normal distribution.
- Select one:
- a. Normal distribution is asymmetric.
- b. Normal distribution is not asymptotic.
- c. Normal distribution is completely described by a single parameter.
- d. Normal distribution is described by the bell curve.
- e. Normal distribution is a discrete distribution.
Find the indicated value of the standard normal variable Z, z.02.
- Select one:
- a. 0.02
- b. -0.02
- c. -2.06
- d. 2.06
- e. 2.05
Let (A) and (B) be two independent events. Their probabilities are \(P(A^c) = \frac{1}{5}), (P(B) = \frac{1}{8}\), and \(P(A | B) = \frac{4}{5}\). Calculate \(P(A \cap B)\).
- Select one:
- a. 3/8
- b. 1/5
- c. 1/10
- d. 5/3
- e. 3/5
Which of the following is the F0.025 test statistic value for \(df_1 = 5\) and \(df_2 = 7\)?
- Select one:
- a. 3.97
- b. 4.88
- c. 5.29
- d. 6.85
- e. 6.88
Compute the sample median for the data: {-5, 4, 8, 5, 2, -1, 3, -6}.
- Select one:
- a. 2
- b. 3
- c. 1.25
- d. 6
- e. 2.5
Consider a random sample of 300 students in a university, 75 of them declared that they like playing football. Construct a 99% confidence interval for the proportion of all students who would like to play football.
- Select one:
- a. [0.186, 0.314]
- b. [0.192, 0.308]
- c. [0.686, 0.814]
- d. [0.692, 0.808]
- e. [0.725, 0.775]
In a study involving dogs, the researcher talks about the summary giving the sample size, sample sizes in select subgroups, and demographics such as the age, the proportion of subjects of each breed, and so on. Which branch of statistics does this signify?
- Select one:
- a. Descriptive statistics
- b. Mathematical statistics
- c. Organizational statistics
- d. Traditional statistics
- e. Inferential statistics
In order to get promoted to the next grade, a student is required to score above 55 in the final test. Assume the scores to be normally distributed with a mean of 60 and a standard deviation of 5.5. Calculate the percentage of students who will be promoted to the next grade.
- Select one:
- a. 18.14%
- b. 81.86%
- c. 67.50%
- d. 62.50%
- e. 52.50%
Which of the following data sets represents a population?
- Select one:
- a. Heights of all students in a college
- b. Scores of a randomly selected group of students
- c. Weights of ten girls in a class of 30 students
- d. Ages of voters who registered on a particular day
- e. Any five day’s temperature readings of the last month
In which of the following situations is a census preferred over a sample?
- Select one:
- a. A study on the number of people in each household in Alaska
- b. A study on the percentage of the Spanish population that has access to the internet
- c. A study on the average lasting of a concrete trade of batteries
- d. A study on the average lifetime of electric bulbs manufactured by a company
- e. A study on the success rate of a particular drug
The measurements of sample elements are collectively called the _____ data.
- Select one:
- a. raw
- b. population
- c. sample
- d. collective
- e. elementary
The probability distribution of a statistic is called its _____.
- Select one:
- a. residual distribution
- b. parametric distribution
- c. statistical distribution
- d. frequency distribution
- e. sampling distribution
Given a population proportion (p = 0.56) and a random sample of size (n = 120), calculate the probability that the sample proportion \(\hat{p}\)Â is less than or equal to (0.6).
- Select one:
- a. 0.115
- b. 0.000
- c. 1.000
- d. 0.811
- e. 0.500
Two hundred randomly selected women in a certain city, including those who are working, were asked the time they spend in the beauty salon for each visit. The average time was 44 minutes with a standard deviation of 16 minutes. Construct an 80% confidence interval for the mean time spent in the salon by all the women in the city.
- Select one:
- a. [43.05, 44.95]
- b. [43.76, 44.24]
- c. [42.55, 45.45]
- d. [43.64, 44.36]
- e. [42.45, 45.55]
In a random sample of size 700, 425 have the characteristic of interest. Identify the statement that justifies why one interval is longer than the other.
- Select one:
- a. The interval is longer because the confidence level is decreased.
- b. The interval is longer because the number of degrees of freedom is decreased.
- c. The interval is longer because the confidence level is increased.
- d. The interval is longer because the number of degrees of freedom is increased.
- e. There is no significant difference between the two intervals.
For a value x in a data set, if P percent of the values are less than or equal to x, then x is called the _____.
- Select one:
- a. Pth percentile
- b. (P + 1)th percentile
- c. (P – 1)th percentile
- d. (P + 1)th quartile
- e. (P – 1)th quartile
Which of the following is not a random experiment?
- Select one:
- a. The selection of a colored ball in a jar
- b. The tossing of a coin
- c. The roll of a die
- d. Percentage of rainfall recorded over a particular hour in a day
- e. An experiment conducted to verify Archimedes’ principle
_____ is the most frequently occurring value in a sample data set.
- Select one:
- a. Sample mean
- b. Sample median
- c. Sample variance
- d. Sample mode
- e. Sample standard deviation
The standard deviation of the sample mean is _____ the standard deviation of the population when the sample size is 2.
- Select one:
- a. equal to
- b. greater than
- c. smaller than
- d. not related to
- e. cannot be determined from the above information
Find the range of the data set {5, 6, 3, 7, 8}.
- Select one:
- a. 1
- b. 2
- c. 6
- d. 5
- e. 4
Sean orders 20 pairs of gloves from an online clothing manufacturer. The site claims that it averages only 12 damaged pair of gloves for every 45,000 pair it produces. What is the probability that there are no defective pieces in his order?
- Select one:
- a. 0.994
- b. 0.006
- c. 0.000
- d. 0.860
- e. 0.140
The probability of winning a certain video game is 0.10. If Jeff plays the game 10 times, what is the probability that he will win at most once?
- Select one:
- a. 0.35
- b. 0.65
- c. 0.74
- d. 0.26
- e. 0.39
For the data set {1.5, 2.3, 1.7, 3.6, 2.9, 4.2} find the second quartile, Q2.
- Select one:
- a. 1.5
- b. 2.9
- c. 1.7
- d. 2.3
- e. 2.6
A random sample of 100 male students is drawn from a particular class. The mean and standard deviation of heights of all male students in the college are 70 inches and 2 inches respectively. Calculate the standard deviation of the sample mean.
- Select one:
- a. 2
- b. 7
- c. 0.7
- d. 0.02
- e. 0.2
A random sample of 7 patients is selected from a group of 25, and their cholesterol levels were recorded as follows: 128, 127, 153, 144, 132, 120, 115. Find the sample mean.
- Select one:
- a. 143.26
- b. 130.32
- c. 131.29
- d. 142.87
- e. 135.16
_____ random variables arise from a counting process.
- Select one:
- a. Normal
- b. Exponential
- c. Indefinite
- d. Continuous
- e. Discrete
A random variable is called _____ if its possible values contain a whole interval of numbers.
- Select one:
- a. normal
- b. definite
- c. discrete
- d. continuous
- e. indefinite
The observed significance of a test of hypotheses is the area of the tail of the distribution cut off by the _____.
- Select one:
- a. rejection region
- b. test statistic
- c. significance level
- d. chance of making a Type II error
- e. sample size
Which of the following is not a random variable?
- Select one:
- a. The amount of rainfall in September
- b. Speed of light in a vacuum
- c. The lifetime of a torch battery
- d. Number of children in a family
- e. Time required to run a mile
A sample of size 25 drawn from a normally distributed population has a sample mean of 12 and a sample standard deviation of 5. Construct an 80% confidence interval for the population mean.
- Select one:
- a. [9.36, 14.64]
- b. [10.68, 13.32]
- c. [10.58, 13.42]
- d. [11.34, 12.66]
- e. [11.44, 12.56]
A continuous random variable X has a normal distribution with a mean of 50. The probability that X takes a value greater than 55 is 0.25. Using this information and the symmetry of the density function, which of the following is the probability that X takes a value less than 45?
- Select one:
- a. 0.30
- b. 0.45
- c. 0.50
- d. 0.55
- e. 0.25
A kindergarten teacher wishes to estimate, to within 3 minutes, the mean time a child takes to arrange a jigsaw puzzle in the class with 90% confidence. Estimate the minimum size of the sample required if the standard deviation of arranging times for the other kindergarten class is 4.2 minutes.
- Select one:
- a. 2
- b. 3
- c. 4
- d. 7
- e. 6
_____ is the number of times a value x appears in a data set.
- Select one:
- a. Statistic
- b. Parameter
- c. Frequency
- d. Rate
- e. Estimator
A restaurant owner wishes to estimate, to within 55 seconds, the mean time taken to serve food to customers with 99% confidence. In the past, the standard deviation of serving time has been about 2.5 minutes. Estimate the minimum size of the sample required.
- Select one:
- a. 40
- b. 41
- c. 48
- d. 49
- e. 50
For large sample tests concerning a single population proportion, the null hypothesis will have the form \(H_0: p = p_0\) where \(p_0\) is some specific number _____.
- Select one:
- a. greater than 1
- b. less than 2
- c. between 0 and 1
- d. between 1 and 2
- e. less than 0
Consider two mutually exclusive events, G and H. Then, we have P(G | H) = _____.
- Select one:
- a. P(G)
- b. P(G) / P(H)
- c. 0
- d. P(H)
- e. 1
A fair die is rolled. What is the probability that the number rolled is less than three?
- Select one:
- a. 1/2
- b. 1/3
- c. 1/4
- d. 1/5
- e. 1/6
A pair of balanced dice are rolled. What is the probability of not rolling doubles?
- Select one:
- a. 1/36
- b. 1/6
- c. 1/18
- d. 1/12
- e. 5/6
For the data set {1.5, 2.3, 1.7, 3.6, 2.9, 4.2}, identify the percentile for the value 2.9.
- Select one:
- a. 50th percentile
- b. 66.67th percentile
- c. 51st percentile
- d. 33.33rd percentile
- e. 49th percentile
A(n) _____ is any subset or subcollection of the population.
- Select one:
- a. parameter
- b. sample
- c. statistic
- d. estimate
- e. estimator
A(n) _____ is a number or attribute computed for each member of a population or of a sample.
- Select one:
- a. statistic
- b. data
- c. measurement
- d. estimator
- e. parameter
A random variable X has the uniform distribution on the interval [0, 1]: the density function is f(x) = 1 if x is between 0 and 1, and f(x) = 0 for all other values of x. What is the probability that X assumes a value greater than 0.90?
- Select one:
- a. 1.00
- b. 0.75
- c. 0.90
- d. 0.10
- e. 0.50
As the sample size of a random sample increases, the standard deviation of the sample mean _____.
- Select one:
- a. remains the same
- b. decreases
- c. increases
- d. becomes less accurate
- e. cannot be determined from the above information
A professor records the difference between the marks scored by the students in the class test last week and those scored in the present week. The mean difference for 35 students was 12 with a standard deviation of 3. Construct a 99.9% confidence interval for the mean difference between the marks scored last week and marks scored this week by all the students.
- Select one:
- a. [10.33, 13.67]
- b. [10.43, 13.57]
- c. [11.04, 12.96]
- d. [11.10, 12.90]
- e. [11.25, 12.75]
A researcher wants to determine the average income of the people of Omaha, Nebraska. He found that there are 385,600 employed people in the state. A group of 1,200 people are selected randomly to ascertain the income of each of those individuals. He finds that the average income of those 1,200 numbers to be $42,827. Identify the sample in this context.
- Select one:
- a. 385,600 employed people in Omaha
- b. 1,200 people selected for the study
- c. Average income of $42,827
- d. 385,600 – 1,200 constitute the population
- e. 385,600 + 1,200 constitute the population
A recently conducted survey indicates that teenagers spend a good amount of their time playing video games. Noel spends about 15 hours per week with a standard deviation of 3 hours. If the amount of time spent playing video games in any given week is normally distributed, then what is the probability that Noel plays video games between 15 and 18 hours a week? Use the empirical rule.
- Select one:
- a. 68.26%
- b. 34.13%
- c. 95.44%
- d. 47.72%
- e. 99.74%
A simple linear regression model is a sum of _____ parts.
- Select one:
- a. two
- b. three
- c. four
- d. five
- e. six
A manager wishes to estimate, to within 1 day, the mean time that employees take to complete an assigned project with 99.8% confidence. With the assumption that the standard deviation of completion times is 3 days, estimate the minimum sample size required.
- Select one:
- a. 85
- b. 86
- c. 74
- d. 75
- e. 60
A survey conducted to determine the textbook expenses states that full-time students spend an average of $250 for textbooks each semester. The standard deviation of the amounts full-time students spend for textbooks per semester is known to be $50. The distribution of the amount spent on textbooks is found to be bell-shaped. What is the probability that a randomly selected student spends more than $300 for textbooks each semester?
- Select one:
- a. 68%
- b. 34%
- c. 32%
- d. 16%
- e. 8%
A sample is large enough for the distribution of sample proportion p to be approximately normal if the interval [p – 3 , p + 3] lies wholly within the interval _____.
- Select one:
- a. [-1, 1]
- b. [-1, 0]
- c. [0, 1]
- d. [0, 2]
- e. [1, 2]
A cell phone manufacturing company claims that the average battery life of its phone is 4 hours. Let us assume that the battery life is normally distributed with a standard deviation of 0.8 hours. What is the probability that the battery life for a randomly selected cell phone is below 3 hours?
- Select one:
- a. 0.9987
- b. 0.8944
- c. 0.1056
- d. 0.0013
- e. 0.9861
The parameter \( \text{df}_2 \) in the F-distribution is often referred to as the:
- Select one:
- a. second degree of freedom.
- b. numerator degree of freedom.
- c. denominator degree of freedom.
- d. first degree of freedom.
- e. df2 degree of freedom.
_____ data are measurements for which there is no natural numerical scale, but which consist of attributes, labels, or other nonnumerical characteristics.
- Select one:
- a. Quantitative
- b. Raw
- c. Contemporary
- d. Qualitative
- e. Descriptive
As a part of his study, a researcher is interested in ascertaining the proportion of people in a locality who are above the age of 80. He takes a random sample of 2,400; 120 of them are above the age of 80, hence 120/2,400 ≈ 0.05 or about 5% are above 80. What is the value of the statistic in this context?
- Select one:
- a. 2,400
- b. 100
- c. 80
- d. 0.05 or 5%
- e. 2,400/120
Consider a random sample size of 400 drawn from a population, and the mean and standard deviation of the sample mean is 100 and 20, respectively. Calculate the standard deviation of the population.
- Select one:
- a. 400
- b. 20
- c. 100
- d. 5
- e. 1
_____ is the branch of statistics that involves organizing, displaying, and describing data.
- Select one:
- a. Inferential statistics
- b. Descriptive statistics
- c. Mathematical statistics
- d. Organizational statistics
- e. Traditional statistics
Find the probability, P(-2 < Z < 2) for a standard normal variable Z.
- Select one:
- a. 0.9544
- b. 0.0228
- c. 0.5000
- d. 0.9772
- e. 0.0456
A chi-square test for independence can be used to evaluate whether _____ are independent.
- Select one:
- a. two pairs of random variables or factors
- b. two random variables or factors
- c. three pairs of random variables or factors
- d. three random variables or factors
- e. five random variables or factors
As the sample size of a random sample increases, the sample mean _____.
- Select one:
- a. becomes less accurate
- b. decreases
- c. increases
- d. becomes more accurate
- e. cannot be determined from the above information
Sample standard deviation is the square root of the _____.
- Select one:
- a. sample mean
- b. population mean
- c. sample variance
- d. population variance
- e. standard error
Sandy Carlson, who plays for her college basketball team, had an 80% free throw percentage in the previous fall semester. On average, Sandy made 8 out of every 10 free throws. If we are to randomly select 80 free throws she has made throughout the season and then record the number of successes in these 80 free throws, then the standard deviation of the sample proportion is:
- Select one:
- a. 0.001
- b. 0.80
- c. 0.04
- d. 0.94
- e. 0.06
For a standard normal variable Z, which of the following z values satisfies the expression: P(Z > z) = 0.57.
- Select one:
- a. 0.18
- b. -0.18
- c. 0.72
- d. -0.72
- e. 0.82
The test statistic for large sample hypothesis tests concerning a single population mean follows _____ distribution.
- Select one:
- a. normal
- b. Student’s t-distribution
- c. no
- d. log-normal
- e. standard normal
A researcher wants to determine the average income of the people of Omaha, Nebraska. He found that there are 385,600 employed people in the state. A group of 1,200 people are selected randomly to ascertain the income of each of those individuals. He finds that the average income of those 1,200 numbers to be $42,827. Identify the population in this context.
- Select one:
- a. 385,600 employed people in Omaha
- b. 1,200 people selected for the study
- c. Average income of $42,827
- d. 385,600 – 1,200 constitute the population
- e. 385,600 + 1,200 constitute the population
The mean and standard deviation of a normally distributed population is 30.5 and 5.0, respectively. Find the probability that the mean of a sample of size 25 drawn from this population is greater than 31.
- Select one:
- a. 0.69
- b. 0.31
- c. 0.54
- d. 0.46
- e. 0.98
For the data set {1.5, 2.3, 1.7, 3.6, 2.9, 4.2, 3.3} find the first quartile, Q1.
- Select one:
- a. 2.0
- b. 2.3
- c. 1.6
- d. 1.7
- e. 1.5
Which of the following is an outcome?
- Select one:
- a. Landing on a head when a coin is tossed
- b. Drawing a card from a shuffled deck of cards
- c. Rolling a pair of dice
- d. Tossing a coin
- e. Choosing a marble from a jar
For a standard normal variable Z, which of the following z values satisfies the expression: P(Z < z) = 0.4840.
- Select one:
- a. 0.32
- b. 0.04
- c. 0.68
- d. -0.32
- e. -0.04
The average number of hamburgers a ten-year-old child eats per month is uniformly distributed from 0 to 4 hamburgers. What is the probability that a randomly selected ten-year-old child eats an average of more than two hamburgers?
- Select one:
- a. 0.25
- b. 0.40
- c. 0.50
- d. 0.30
- e. 0.75
The coefficient of determination can be computed simply by squaring _____.
- Select one:
- a. the slope, if it is already known.
- b. the y-intercept, if it is already known.
- c. the sample standard deviation of errors, if it is already known.
- d. the correlation coefficient, if it is already known.
- e. the sum of the squared errors, if it is already known.
A model is a set of assumptions in simple linear regression which are:
- Select one:
- a. a logical description of the relationship between x and y.
- b. a mathematical description of the relationship between x and y.
- c. descriptions of the type of the relationship between x and y.
- d. a set of descriptions of the relationship between x and y.
- e. a graphical description of the relationship between x and y.
A manager monitors the time spent by employees for coffee breaks during working hours. For a random sample of 38 employees, the average amount of time spent for breaks in a nine-hour workday was 32.6 minutes with a standard deviation of 5.3 minutes. Construct a 98.5% confidence interval for the mean time spent by all the employees for breaks in a nine-hour day.
- Select one:
- a. [31.79, 33.41]
- b. [30.51, 34.69]
- c. [31.73, 33.47]
- d. [30.73, 34.47]
- e. [31.69, 33.51]
