Question

The average age of CEOs is 56 years. Assume the variable is normally distributed. If the standard deviation is 4 years, find the probability that the age of a randomly selected CEO will be in between 50 and 55 years old. Give the probability as a decimal rounded to four decimal places.

Answer 1

P(-1.5<z< -0.25) =P(Z< -0.25)-P(Z< -1.5) = 0.4013 - 0.0668 = 0.3345 (FROM Z TABLE )

where P(z<-0.25 ) = 1-P(z<0.25) = 1- 0.5987 = 0.4013(from z table )

and P(Z< -1.5) = 1-P(z<1.5) = 1-0.9332 = 0.0668 (from z table )