prob. dist.: John runs a store. Yesterday he counted....

Use the following information for the next 4 questions:

John runs a computer software store. Yesterday he counted 126 people walk by the store, 57 of whom came into the store. Of the 57, only 24 bought something in the store.

a) What is the probability that a person who walks by the store will enter?

b) What is the probability that a person who walks in will buy something?

c) What is the probability that a person who walks by will come in and buy something?

d) What is the probability that a person who comes in will buy nothing?

I don't even know how to start this one

Hint: Given x successes out of y trials, what is the expected probability of a success in the next trial?

Eliz.