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Determine the variance and standard deviation of the following sample:
12, 6, 22, 31, 23, 13, 15, 17, 21
Determine the standard deviation of the following sample:
10,10,14,16,8,8
SAT Math scores in recent years have had means around 490 and standard deviations around 10. What is the variance of SAT Math scores? (in this case, treat as a population)
Consider the following three data sets (treat as a population):
A = {9,10,11,7,13} B = {10,10,10,10,10} C = {1,1,10,19,19}
a. Calculate the mean of each data set.
b. Calculate the standard deviation of each data set.
c. Which set has the largest standard deviation?
Duke University’s football team wants to describe the distribution of head sizes of its players in order to plan orders of helmets. Here are the head sizes (in inches) of 30 football players
23.0 22.2 21.7 22.0 22.3 22.6 22.7 23.3 21.5 22.7 24.9 20.8 24.2 23.5
23.9 23.4 20.8 21.5 23.0 24.0 22.7 22.6 23.9 21.8 23.1 21.9 21.0 22.4 23.5 22.5
a. Find the µ and “σ” for these data. Be sure to include the units in which these numbers
are measured.
The frequency table includes the monthly salaries of 20 people working at McDonald’s.
Salary (in$) Frequency
3500 5
4000 8
4200 5
4300 2
a. Calculate the mean of the salaries of the employees in this table
b. Calculate the standard deviation of the sample salaries of the 20 people.
