Question 386673
a) In the case of replacement, we need to pick the D out of all 6 letters (P = 1/6), then we need to pick the A out of all 6 (P = 1/6), then we need to pick the N out of all 6 (P = 1/6). We multiply the probabilities together since they must all occur. So, the answer is (1/6)*(1/6)*(1/6) or 1/216.

b) In the case without replacement, we must first pick the D out of all 6 letters (P = 1/6), then we must pick the A out of the remaining five letters (P = 1/5), then we must pick the N out of the remaining 4 letters (P = 1/4). We multiply the probabilities together since they must all occur. So, the answer is (1/6)*(1/5)*(1/4) or 1/120.