The number may be calculated as (0.79) ^ 4 = 0.3895 = 0.400.
This is becasue the probability of finding each adult having health insurance is independent of others.
When, events are independent, the combined probability is the product of each probability =>
Probailibty of one adult with healt insurance probability of one adult with healt insurance probability of one adult with health insurance probability of one adult with health insurance = 0.79 * 0.79 * O.79 * 0.79 = (0.79) ^ 4.
