Intro Mean, Median & Standard Deviation Exercises
1. A health food company employs 20 workers whose salaries (in dollars) are
14000 10000 16400 21795 17000 12000 18200 24500 16000 26000
17950 15000 18000 7000 16280 9050 9000 13500 19640 7620
Find the range of salaries for the 20 workers.
2. The following grades were obtained on a statistics test:
68
98
83
55
76
80
85
95
Find the range of the grades.
93
50
59
90
69
73
96
80
86
85
84
90
78
80
80
97
65
3. A secretary types 10 business letters for her supervisor. The number of typing errors per letter
was 4, 2, 0, 3, 8, 2, 6, 1, 9, and 0. Find the standard deviation and range for the numbers.
4. The ages of the members of a math department are 31, 28, 44, 39, 52, 39, 58, and 29 years.
Calculate the standard deviation for the ages.
5. Trudy loves to speak on the telephone. Last night she made 6 calls which lasted 44, 11, 32,
27, 48, and 18 minutes. Find the mean and standard deviation for the length of a telephone
call.
6. Each year many television stations conduct fund raising drives through telethons for various
charities. For the past 5 years one television station kept records on the time that passed before
the first $ 10,000 was pledged. This information follows:
Minutes Passed Before
Year
First $10,000 was Pledged
1972
19
1973
12
1974
10
1975
19
1976
5
Find the mean and standard deviation for the numbers
7. The number of minutes that a commuter waited for her train during one week was 10, 6, 15,
11, and 3. Calculate the mean & standard deviation.
8. Multiply each number in exercise #7 by 3 and then compute the mean and standard deviation
for the new distribution. How do the results compare with those of the preceding exercise?
Can you generalize?
9. A comparison shopper has compared the prices of a pound of ground beef at a number of
different supermarkets. The following prices, in cents, were obtained: 89, 93, 74, 63, and 101.
a)
b)
c)
d)
Calculate the mean and standard deviation of each price
Calculate the mean and standard deviation by subtracting 25 cents from each price.
Calculate the mean and standard deviation by subtracting 80 cents from each price.
How are the mean and standard deviation affected if we subtract different numbers
from each price?
10. The average cost of malpractice medical insurance last year in a certain city was $2300 for a
neurosurgeon, with a standard deviation of $450. This year, rates will be increased by $600.
What will the new mean and standard deviation be?
11. Last year Sam bought 5 tires, which lasted 17,010, 16,080, 17,050, 16,090, and 17,000 miles.
Find the standard deviation for the life of the tires.
Answers
1. Range is $26,000 - $7000 = $19,000.
2. Range is 98 – 50 = 48
3. Range is 9 – 0 = 9. Standard deviation is 3.04
4. Standard deviation = 10.20
5. Mean = 30. Standard deviation 13.15
6. Mean = 13. Standard deviation = 5.40
7. Mean = 9. Standard deviation = 4.15
8. Mean = 27. Standard deviation = 12.44. They are 3X the previous values.
9. a. mean = 84  =13.7 b. Mean = 59 =13.7 c. Mean = 4 =13.7 d. mean changes by that
subtracted,  remains the same.
10. Mean = $2900. Standard deviation = $450
11. Standard deviation = 24.17