Question

Given that z is a standard normal random variable, compute the following probabilities (to 4 decimals).
P(z -1.0)


P(z -1.0)


P(z -1.5)


P(z -2.5)


P(-3 < z 0)

Answer 1

P(z <-1.0) = 0.1587


P(z <-1.5) = 0.0668


P(z <-2.5) = 0.0062


P(-3 < z < 0) = 0.500-0.0013

Answer 2

Jim Tree sells Christmas trees. The mean length of the trees purchased was 68 inches with a standard deviation of 10 inches. Jim wants to know what per cent of his sales were more than 84 inches tall. He can use the standard normal distribution to help him.