Question

A supermarket uses two suppliers, C and D, of strawberries. Supplier C supplies 70% of the supermarket’s strawberries. Strawberries are examined in a quality control inspection (QCI); 90% of the strawberries supplied by C pass QCI and 95% of the strawberries from D pass QCI. A strawberry is selected at random.

a)    Find the probability that the strawberry passes QCI.

b)    Given that a strawberry passes QCI, find the probability that it came from supplier D.

c)    In a sample of 2000 strawberries, find the expected number of strawberries that would fail QCI.

d)    The supermarket wants the probability that a strawberry passes QCI to be 0.93. Find the percentage of strawberries that should be supplied by D in order to achieve this.

Answer 1