An experimental drug was given to a sample of

99

hospital patients with an unknown sickness. Of the total,

71

patients reacted favorably,

13

reacted unfavorably, and

15

were unaffected by the drug. Assume that this sample is representative of the entire population. If this drug is given to Mr. and Mrs. Rivera and their son Carlos, what is the probability that all three react favorably? (Assume independence.)