A food store just got a delivery of 10000 potatoes It is kno

A food store just got a delivery of 10000 potatoes. It is known that each potato is rotten with probability 0.1. What is the expected number of healthy potatoes? Use the normal approximation to estimate the probability that there are at least 8970 healthy potatoes.

Solution

P( x > 8970)

miu ( mean ) of healthy poptatoes= 10,000 * 0.9 = 9,000

SD = srqt ( 10,000 * 0.9 * 0.1 ) = 30

P( z > (8970-9000) / 30 )

P( z > -1) = 1- P( z< -1) = 1 -0.1587 = 0.8413