A new extended-life light bulb has an average life of 750 hours,with a standard deviation of 50 hours. If the life of these light bulbs approximates a normal distribution,about what percent of the distribution will be between 600 hours and 900 hours?
A)95%
B)68%
C)34%
D)99.74%

Question

Quizplus · Accepted Answer

Using the empirical rule for normal distributions, 99.74% of the data falls within three standard deviations from the mean. Here, 600 hours is three standard deviations below the mean (750 - 3*50), and 900 hours is three standard deviations above the mean (750 + 3*50).

A New Extended-Life Light Bulb Has an Average Life of 750