Question

The demand for a product is Normally distributed with mean 2000 and standard deviation 150. What is the probability that demand is less than 1800, that is P(X<1800)? Choose the best possible answer (just ONE answer).

0.0011

less than 0.5

None of the above/below

0.91

0.0912

Answer 1

Probability that demand is less than 1800 or P(X<1800) is same as P(Z<(1800-2000)/150)=P(Z<-1.333333333)
From z table we see that
P(Z<-1.333333333)=0.09121122