The expected (mean)life of a particular type of light bulb is 1,000 hours with a standard deviation of 50 hours. The life of this bulb is normally distributed. What is the probability that a randomly selected bulb would last longer than 1150 hours?
A) 0.4987
B) 0.9987
C) 0.0013
D) 0.5013
E) 0.5513

Question

Quizplus · Accepted Answer

To find the probability that a bulb lasts longer than 1150 hours, we calculate the z-score: z = (1150 - 1000) / 50 = 3. The probability of a z-score greater than 3 is 0.0013.

The Expected (Mean)life of a Particular Type of Light Bulb