Statistics

QUESTION 1
1.    In a unimodal distribution, the mode equals 60, the median equals 54, and the mean equals 51. Which

of the following best describes the distribution?

normally distributed

positively skewed

negatively skewed

cannot be determined

QUESTION 2
1.    A z-score of z = 3.25 indicates a location that is:

near the center of the distribution

slightly below the mean

slightly above the mean

far above the mean

far below the mean

the location depends on the mean and standard deviation for the distribution

QUESTION 3
1.    A z-score of z = -3.00 indicates a position in a distribution that is located:

below the mean by 3 raw score points

below the mean by a distance that is 3 times the mean

below the mean by a distance that is 3 times the standard deviation

below the mean by a distance that is 3 times the variance

QUESTION 4
1.    A study finds those at a higher percentile of heights are also more likely to have certain health

problems including multiple cancers, heart disease, and Alzheimer’s. Which of the following individuals is

most likely to develop a health problem?

Miranda whose height is 1 standard deviation above the mean

Callie whose height corresponds to a z-score of z = -1.77

Christina whose height is between 0.75 and 2.21 standard deviations above the mean

Meredith whose height corresponds to a z-score of 2.33

QUESTION 5
1.    Last week Derrick had a stress test and an electrocardiogram (ECG) done after experiencing chest

pains.  He scored 10 points below the mean on both exams.  From this information, which of the following

conclusions can be made?

Derrick has identical z-scores for both tests

Derrick’s z-scores on both tests are positive

Derrick will have a higher z-score for the test with the lower mean

none of the above

QUESTION 6
1.    A population has a mean of 28 and a standard deviation of 2.  If the scores in the population are

transformed to standard scores (z-scores), the population of z-scores will have a mean of ____ and a

standard deviation of ____.

0 and 2

28 and 2

0 and 1

28 and 1

QUESTION 7
1.    A variable follows a normal distribution with a mean of 12 and a standard deviation of 3. What is

the z-score for an observed value of 15?

z = -1

z = +1

z = -0.67

z = +0.67

QUESTION 8
1.    A variable follows a normal distribution with a mean of 12 and a standard deviation of 3. What is

the value of the variable whose z-score is -2.5?

X = -19.5

X = -3.5

X = +9.5

X = +4.5

X = +10.375

QUESTION 9
1.    In a standard normal distribution, what proportion of the distribution is above z = -0.75?

0.7734

0.2266

0.7704

0.2296

not enough information provided

QUESTION 10
1.    In a standard normal distribution, what proportion of the distribution is between z = 0.4 and z =

1.2?

0.6554

0.2295

0.8413

0.8849

not enough information provided

QUESTION 11
1.    In a standard normal distribution, approximately what z-score separates the upper 4% of the data

from the lower 96% of the data?

z = -1.65

z = +1.75

z = +1.96

z = +3.08

not enough information provided

QUESTION 12
1.    Consider the boxplot below.

What percent of observations are below 14?

10%

20%

25%

50%

not enough information provided

QUESTION 13
1.    Consider the boxplot below.

What percent of observations are between 8 and 14?

25%

40%

50%

75%

not enough information provided

QUESTION 14
1.    The histogram displays the number of days spent hospitalized by a sample of patients with COPD.

What is the sample size?

6

41

87

100

QUESTION 15
1.    The histogram displays the number of days spent hospitalized by a sample of patients with COPD.

Which interval would include a patient with a stay of 14 days?

2

3

4

not enough information

QUESTION 16
1.    The histogram displays the number of days spent hospitalized by a sample of patients with COPD.

The x-axis is labeled with class midpoints. For the class with a midpoint of 7, what is the upper bound?

9

9.5

10

not enough information

QUESTION 17
1.    Consider the following set of data for the variable X:
1  2  4  4  5  8
What is N?

QUESTION 18
1.    Consider the following set of data for the variable X:
1  2  4  4  5  8
What is    ?

QUESTION 19
1.    Consider the following set of data for the variable X:
1  2  4  4  5  8
What is     ?

QUESTION 20
1.    Consider the following set of data for the variable X:
1  2  4  4  5  8
What is     ?

QUESTION 21
1.    Consider the following set of data for the variable X:
1  2  4  4  5  8
What is the variance of the sample?

QUESTION 22
1.    Consider the following set of data for the variable X:
1  2  4  4  5  8
What is the first quartile, Q1?

QUESTION 23
1.    Consider the following set of data for the variable X:
1  2  4  4  5  8
What is the second quartile, Q2?

QUESTION 24
1.    Consider the following set of data for the variable X:
1  2  4  4  5  8
What is the third quartile, Q3?

QUESTION 25
1.    Total fingerprint ridge count in humans is approximately normally distributed with mean of 140 and

standard deviation of 35. (3 pts each) NOTE: use leading zeros before a decimal when appropriate, z-scores

should have two decimal places, proportions will have four decimal places, and there are no percentages in

this set of items.

(1) What is the z-score for a person having 120 ridges?
(2) What proportion of the population has more than 160 ridges?
(3) What is the z-score for a person having 80 ridges?
(4) What proportion of the population has between 80 and 110 ridges on a fingerprint?
(5) In answering the following question, “What is the minimum number of ridges a person must have to be
considered in the top 15% of the number of fingerprint ridges?” what z-score corresponds to the top 15%?
(6) What is the minimum number of ridges a person must have to be considered in the top 15% of the number of
fingerprint ridges?

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