Question

A certain club has 10 members, including Harry. One of the 10 members is to be chosen at random to be the president, one of the remaining 9 members is to be chosen at random to be the secretary, and one of the remaining 8 members is to be chosen at random to be the treasurer. What is the probability that Harry will be either the member chosen to be the secretary or the member chosen to be the treasurer?

A) 1/720B) 1/80C) 1/10D) 1/9E) 1/5

Answer 1

Answer: E) 1/5

Explanation:

The probability of any member being selected for each of the 3 posts is 1/10 that is they have equal probabilities of being selected for any of the posts.

The probability that harry would be selected for;

Secretary Ps= 1/10

Treasurer Pt = 1/10

So the probability of being selected for either secretary or treasurer is

P = Ps + Pt

P = 1/10 + 1/10

P = 2/10

P = 1/5

Note: ignore the sequence of selection