Question

Suppose a large shipment of cell phones contained 13% defectives. If a sample of size 284 is selected, what is the probability that the sample proportion will be less than 11%? Round your answer to four decimal places.

Answer 1

n = 284

p = 0.13

= p = 0.13

= sqrt(p(1 - p)/n)

= sqrt(0.13 * (1 - 0.13)/284) = 0.02

P( < 0.11)

= P(( - )/ < (0.11 - )/)

= P(Z < (0.11 - 0.13)/0.02)

= P(Z < -1)

= 0.1587