Answer the questions:

a) A population variance is computed to be 81. What is the standard deviation?

b) A sample standard deviation is computed to be 4.5. What is the variance?

c) What is the standard deviation of the 6 grades (shown below) from a Statistics midterm?

85 85 85 85 85 85

d) Which group has the most variation? (Which one is the correct group?)

A B C

Mean 75.5 75.7 75.2

Standard Deviation 3.2 0.8 2.5

e) For an exam given to a class, the students' scores ranged from 25 to 95, with a mean of 65.

What is the most realistic value for the standard deviation (Choose): -10 0 3 70