[EX02-165] A random sample of people of all ages was taken from the U.S. population, and the resulting 75 ages (in years) are listed in the following table:

22 7 72 32 18 4 9 48 49 18 18 58 47 39 48 1 27 61 48 25 34 75 29 53 37 25 42 49 29 31 10 27 8 78 63 50 39 32 5 39 8 15 8 50 39 46 38 4 9 43 3 65 25 67 19 9 34 8 36 48 56 73 24 20 34 38 45 40 11 40 37 17 63 9 91

a. Construct a grouped frequency distribution for the ages using class midpoints of 0, 10, 20, . . .

90. Show the class midpoints and the associated frequency counts in your table.

b. Construct a histogram.

c. Does the variable “age” appear to have an approximately normal distribution?

d. Calculate the mean age.

e. Find the median age.

f. Find the range of ages.

g. Find the standard deviation of ages.

h. Compare the values found in parts d through g against corresponding statistics calculated using the given ungrouped data. Use the percent error in each case, and present all results in a table to make your case.