The table gives the projected 2020 population of the United States.

(a) Use the class marks and the given number (frequency) in each class to find the mean age.

(b) In third world countries where the birth rate is higher and the life span is shorter, which group—under 30, 30–59, or 60 and over—would be most likely to be the smallest? How would this affect a third world country’s mean age relative to that of the United States?

Transcribed Image Text:

Age Class Mark Number (millions) Under 15 7 68.1 15-29 22 67.3 30-44 37 66.8 45-59 52 63.3 60-74 67 53.3 Over 75 82 22.5