Assume the mean useful life of a particular lightbulb is 2,000 hours and is normally distributed with a standard deviation of 300 hours. Calculate the useful life of lightbulbs within two standard deviations of the mean.
A)Between 1,700 and 2,300 hours
B)Longer than 2,300 hours
C)Longer than 1,700 hours
D)Between 1,400 and 2,600 hours

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The Answer of Assume the mean useful life of a particular lightbulb is 2,000 hours and is normally distributed with a standard deviation of 300 hours. Calculate the useful life of lightbulbs within two standard deviations of the mean.
A)Between 1,700 and 2,300 hours
B)Longer than 2,300 hours
C)Longer than 1,700 hours
D)Between 1,400 and 2,600 hours

Assume the Mean Useful Life of a Particular Lightbulb Is