Question: The life of a certain light bulb averages 1000 hours with a standard deviation of 75 hours. What is the probability that a randomly selected bulb lasts:

a. from 950 to 1050 hours?

b. from 900 to 1100 hours?

c. from 850 to 1150 hours?

d. from 800 to 1200 hours?

e. from 750 to 1250 hours

Look at your answers a to e. What pattern do you see? What happens as the interval increases in size? Explain why. Is the increase in probability linear? Why?