Refer to the study discussed in Exercise 8.69. The accompanying table shows the results of the study

Question:

Refer to the study discussed in Exercise 8.69. The accompanying table shows the results of the study for different age groups.

a. For each age group, find the percentage who were smiling.
b. Treat this as a random sample of people, and merge the groups 0€“10 and 11€“20 into one age group (0€“20) and the groups 21€“40, 41€“60, and 61+ into another age group (21 -65 +). Then determine whether these two age groups have different proportions of people who smile in the general population, using a significance level of 0.05. Please comment on the results.