Answer
a) 12,650
b) 303,600
Work Step by Step
a) Since the order of choosing the members is irrelevant, we use a combination.
Therefore, the answer is ${^{25}C_4}$ = 12,650.
b) We need to choose four people, first a president, then a vice
president, then a secretary, then a treasurer. Since the order matters, so we use permutation.
Therefore, answer is $^{25}P_4 $= 303,600.