Chapter 10 Counting Methods and Probability - 10.3 Define and Use Probability - Guided Practice for Examples 3 and 4 - Page 700: 6

See below.

Using the example, the total number of people surveyed is: $3516$. a) Of those surveyed $463+1085+879=2427$ would prefer to be at most $39$ years old. Hence the probability: $\frac{2427}{3516}\approx0.69$ b) Of those surveyed $879+551+300+238=1968$ would prefer to be at most $39$ years old. Hence the probability: $\frac{1968}{3516}\approx0.56$