Question

The one-time fling! Have you ever purchased an article of clothing (dress, sports jacket, etc.), worn the item once to a party, and then returned the purchase? This is called a one-time fling. About 15% of all adults deliberately do a one-time fling and feel no guilt about it! In a group of seven adult friends, find the following probabilities.
(a) No one has done a one-time fling. (Use 3 decimal places.)
(b) At least one person has done a one-time fling. (Use 3 decimal places.)

(c) No more than two people have done a one-time fling. (Use 3 decimal places.)

Answer 1

(a): If the probability of doing a one-time fling is 15%, then the probability of not doing the one time fling would be 85% (100%-15%). To find the probability of this being true for seven people, you would take (.85)^7

Answer 2

(b): you need to find the probability that zero people do a one-time fling. Then subtract that number from 1.

Answer 3

(c): No more than two people means the same thing as the probability that only zero, one, or two people have done a one time-fling.

You need to add the probability that zero people fling, with the prob that one person does, with the prob that two people do. This sum P(fling<=2)

Answer 4

The is also a binomial distribution function...you can use your calculator for this if you're technologically inclined.