3.39 Using the data in Exercise 3.5, construct a frequency distribution.

a. Determine the approximate values of the mean and standard deviation.

b. Compare the approximate values from part

(a) with the actual values.

c. Construct a frequency distribution with twice as many classes as before, then repeat parts

(a) and (b).

Have the approximations improved?

d. If you were to construct a “frequency distribution”

in which each data value was at the midpoint of its own class, what values do you think the

“approximations” would have? Explain.