The lifespan of a 60-watt lightbulb produced by a company is normally distributed with a mean of 1450 hours and a standard devia
tion of 8.5 hours. if a 60-watt light bulb produced by this company is selected at random, what is the probability that its lifespan will be between 1440 and 1465 hours
To evaluate the probability that the lifespan will be between 1440 and 1465 hours will be given by: P(1440<x<1465) using the z-score formula we obtain: z=(x-μ)/σ where: μ=1450 σ=8.5 hence when x=1440 z=(1440-1450)/8.5 z=-1.18 P(z<-1.18)=0.1190
when x=1465 z=(1465-1450)/8.5 z=1.77 P(z<1.77)=0.9625
