The life of a Radio Shack record player is normally distributed with a mean of 3.2 years and a standard deviation of 0.8 years. Radio Shack guarantees its record players for 2 years.

Question

(a) Find the probability that a record player will last less than 2 years?

(a) Find the probability that a record player will last more than 4 years?

Answer 1

Let X= life of a record player and Z= a standard normal.

(a) P(X<2)=P(Z<(2-3.2)/0.8)=P(Z<-1.5)= 0.0668

(b) P(X>4)=P(Z>(4-3.2)/0.8)=P(Z>1)=0.159