Math 50 – Section #4.2 Name ____________________

Measures of the Spread

Professor Jason Wang

1. The following data set represents the ride time of various roller coaster rides that

are made out of wood in Ohio.

63 90 90 93 105 120 140 193 250

Use this information to find each of the following values. Include the correct

units all your answers and round to 1 decimal place, where applicable.

Range: Standard Dev: Variance:

2. The following data set represents the number of credit hours (CH) that a sample

of students enrolled in during a semester.

16 10 11 13 13 15 15 13 15 17 13 14

11 12 14 14 16 12 15 11 13 10 13 10

15 15 16 8 13 16 14 12.5 14 18 4 13

11 13 5

Use this information to answer each of the following questions. Include the

correct units all your answers and round to 1 decimal place, where applicable.

(a) Find each of the following values.

x = Med = M = Range =

s =

2

s =

(b) Complete the below frequency table for this data set

Number of Credit Hours (CH) Number of Students

4 – 5

6 – 7

8 – 9

10 – 11

12 – 13

14 – 15

16 – 17

18 – 19

(c) Using your frequency table that you just

filled out, construct a histogram for this data set.

(d) Does the Empirical Rule apply? Why or why not? Briefly explain your answer.

(e) According to the Empirical Rule, approximately what percentage of the

observations in this data set fall within one standard deviation of the mean?

(f) Use the data set to determine the actual percentage that fall within one

standard deviation of the mean. (This will require you to calculate a percentage.)

(g) Is the observation of a student enrolled in 4 credit hours (CH) unusual?

Why or why not? Briefly explain your answer.

(h) A student concludes that the mean and standard deviation describe the

center and the spread of the numbers of credit hours for ALL students

enrolled at the college. What would you tell this student? Briefly explain

your answer.