A local downtown arts and crafts shop found from past observation that ...

A local downtown arts and crafts shop found from past observation that 15% of the people who enter the shop actually buy something. Three potential customers enter the shop.

a. How many outcomes are possible for whether the clerk makes a sale to each customer? Construct a tree diagram to show the possible outcomes. Let Y=sale, N=no sale.

b. Find the probability of making at least one sale to the 3 customers.