# Statistics: Quartiles, Distribution

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1. Find the third quartile Q3 of the list of 24 sorted values shown below.

35 35 42 42 43 43 43 45 46 47 49 50 51 54 55 56 57 59 63 64 67 69 74 77

The third q2uartile Q3 is _____ (type an integer or a decimal.)

2. Which is relatively better: a score of 81 on a psychology test or a score of 50 on a economics test? Scores on the psychology test have a mean of 88 and a standard deviation of 9. Scores on the economics test have a mean of 61 and standard deviation of 5.

a. the psychology test score is relatively better because its z score is greater thatn the z score for the economics test score.

b. the economics test score is relatively better because its z score is greater thatn the z score for the psycholoy test score.

c. the psychology test score is relatively better because its z score is less than the z score for the economics test score.

d. the economics test score is relatively better because its z score is less than the z score for the psychology test score.

3. Identify the type of observational study (cross-sectional, retropective, or prospective) described below.

A reasearch company uses adevice to record the viewing habits of about 12,500 households, and the data collected today will be ued to determine the proportion of households tuned to a particular sports program.

Which type of observatinal stydy isdescribed in the problem statement?

a. a prospective study

b. a cross-sectional study

c. a retrospective study

4.

a. Convert the fraction 3/10 to an equivalent percentage.

b. Convert 32.1% to an equivalent decimal

c. What is 23% of 200?

d. Convert 0.514 to an equivalent percentage.

5. The Gallup Organization contacts 1361 adult men who are 40 to 60 years of age and live in the United States and asks whether or not they had seen their family doctor within the past 6 months.

a. What is the population in the study?

b. What is the sample of the study?

#### Solution Preview

1. First, line up the numbers in order (as it is already displayed). Divide the set into quarters. (Literally with a pencil.) Do this by first dividing the list in half (so with our case, a vertical line between the "50" and the "51"). Next, do the same with the right hand side and the left hand side.

You will have 3 lines when you are finished (four "quarters".) The line first from the left is Q1, then moving towards the right, Q2 will be next (this will be the first line you drew), then continuing toward the right, Q3 is next.

Here's the trick: If our line falls in between ...

#### Solution Summary

The solution determines the quartiles and distribution.