# Question: Suppose that the burning times of electric light bulbs approximate

Suppose that the burning times of electric light bulbs approximate a normal curve with a mean of 1200 hours and a standard deviation of 120 hours. What proportion of lights burn for

(a) Less than 960 hours?

(b) More than 1500 hours?

(c) Within 50 hours of the mean?

(d) Between 1300 and 1400 hours?

(a) Less than 960 hours?

(b) More than 1500 hours?

(c) Within 50 hours of the mean?

(d) Between 1300 and 1400 hours?

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