Question

A new extended-life light bulb has an average life of 750 hours, with a standard deviation...

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 650 hours and 850 hours?

Seleccione una:

A. 95%

B. 68%

C. 99%

D. 34%

Math   Statistics-And-Probability   
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Answer #1

                                         

                                          = P(-1 < Z < 1)

                                          = 68% (ans)

Option-B) 68%

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