Posted by **Stephanie F** on Tuesday, December 13, 2011 at 3:45pm.

A new extended-life light bulb has an average service life of 750 hours, with a standard deviation of 50 hours. If the service life of these light bulbs approximates a normal distribution, about what percent of the distribution will be between 600 and 900 hours?

a. 95 percent

` b. 68 percent

c. 34 percent

d. 99.7 percent

e. cannot be determined from the information given.

also please explain how you get the answer...

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