Chapter 3 Quiz and Study Guide

Question 1

A normal population has 99.73% of the population measurements within _______ standard deviation(s) of the mean.
a. 4
b. 3
c. 2
d. 1

Answer 1

b. 3

Question 2

All of the following are measures of central tendency except:
a. mode
b. median
c. mean
d. range

Answer 2

d. range

Question 3

Which percentile describes the first quartile, Q1?
a. 75th
b. 100th
c. 50th
d. 25th

Answer 3

d. 25th

Question 4

If a population distribution is skewed to the right, then, given a random sample from that population, one would expect that the:
a. median would be equal to the mean
b. mode would be equal to the mean
c. median would be less than the mean
d. median would be greater than the mean

Answer 4

c. median would be less than the mean

Question 5

A quantity that measures the variation of a population or a sample relative to its mean is called the:
a. coefficient of variation
b. standard deviation
c. range
d. variance

Answer 5

a. coefficient of variation

Question 6

The _________ is the positive square root of the sample variance.
a. sample standard deviation
b. median
c. range
d. sample mean

Answer 6

a. sample standard deviation

Question 7

Which of the following is a measure of the strength of the linear relationship between x and y that is dependent on the units in which x and y are measured?
a. least squares line
b. slope
c. covariance
d. correlation coefficient

Answer 7

c. covariance

Question 8

A measurement located outside the upper limits of a box-and-whiskers display is:
a. always in the first quartile
b. an outlier
c. always the largest value in the data set
d. within the lower limits

Answer 8

b. an outlier

Question 9

If the mean is greater than the median, then the relative frequency curve is most likely to
be ________.
a. skewed right
b. skewed left
c. symmetrical
d. bimodal

Answer 9

a. skewed right

Question 10

As the coefficient of variation ________, risk ________.
a. increases, decreases
b. decreases, increases
c. increases, increases
d. remains constant, increases

Answer 10

c. increases, increases

Question 11

In the least squares line, ________ is defined as rise/run.
a. correlation coefficient
b. predicted value of y
c. y-intercept
d. slope

Answer 11

d. slope

Question 12

Find the z-score for an IQ test score of 92 when the mean is 100 and the standard deviation is 15.
a. .53
b. .77
c. −.77
d. −.53
e. −8.00

Answer 12

d. −.53

(z-score = (x - mean) / standard deviation, so (92-100)/15 = -0.53

Question 13

Find the z-score for an IQ test score of 118 when the mean is 100 and the standard deviation is 15.
a. 1.2
b. 1.0
c. 18.0
d. −1.03
e. −1.2

Answer 13

a. 1.2

Question 14

According to a survey of the top 10 employers in a major city in the Midwest, a worker spends an average of 413 minutes a day on the job. Suppose the standard deviation is 26.8 minutes, and the time spent is approximately a normal distribution.
What are the times within which approximately 68.26 percent of all workers will fall?
a. [394.8, 431.2]
b. [386.2, 439.8]
c. [372.8, 453.2]
d. [359.4, 466.6]
e. [332.6, 493.4]

Answer 14

b. [386.2, 439.8]

(68.26% means within the mean plus or minus standard deviation zone, so:
1. do 413 - 26.8 = 386.2
2. do 413 + 26.8 = 439.8)

Question 15

In a statistics class, 10 scores were randomly selected with the following results (mean = 71.5): 74,
73, 77, 77, 71, 68, 65, 77, 67, 66.
What is the range?
a. 22.72
b. 12.00
c. 4.77
d. 516.20
e. 144.00

Answer 15

b. 12.00

(77 is the highest number - 65 which is the lowest number = 12)