Question

A fast food restaurant sells burgers, chicken sandwiches, and entree salads. If a customer buys a burger, the probability they buy french fries is 0.80. Fifty percent of customers who purchase a chicken sandwich also buy fries, but only 10% of those buying an entree salad buy fries. Of all customers, 65% buy a burger, 20% a chicken sandwich, the rest buy an entree salad.

What proportion of customers get a burger and fries?

Answer 1

52%

Explanation:

We are told that, of all customers 65% buy a burger. This would imply that the proportion of customers who buy a burger is 0.65.

Moreover, if a customer buys a burger, the probability they buy french fries is 0.80. This implies that the proportion of customers who buy fries given that they bought a burger is 0.8.

Therefore, the proportion of customers who get a burger and fries is simply the product of the two probabilities;

= 0.65*0.8

= 0.52

Therefore, 52% of all customers get a burger and fries