Answer:
10.2% of adults will belong to health clubs and will go to the club at least twice a week
Explanation:
assuming that the event H=an adult belongs to a health club and the event T= he/she goes at least twice a week , then if both are independent of each other:
P(T∩H)= P(H)*P(T) ( probability of the union of independent events → multiplication rule )
replacing values
P(T∩H)= P(H)*P(T) = 0.20 * 0.51 =0.102
then 10.2% of adults will belong to health clubs and will go to the club at least twice a week