<span>Let p be the probability that an adult was never in a museum. Hence p = 0.15. Then q is the probability that an adult was in a museum is 1 - 0.15 = 0.75. We have a binomial expansion where the probability of k success in n trials is given by
P_n(k) = (n, k) p^(k) q^(n -k) where (n, k) is the number of ways to select 10 objects from k things.
At least two or fewer means we have P_10 (< or equal to 2)
So we have P_10 (less than or equal to 2) = P_10 ( 0) + P_10 (1) + P_10 (2).
So we have P _10 (0) = ( 10, 0) (0.15)^ (0) (0.75)^(0) = 0.196. For P_10(1), we have 0.3474 and for P_10(2), we have 0.2758. Adding these we have 0.1960 + 0.3474 + 0.2758 = 0.8192.</span>
