Suppose 6
Suppose the life span of a revolutionary light bulb is normally distributed with a mean life span of 70 thousand hours and a standard deviation of 3 thousand hours. If a light bulb is chosen at random:
a) what is the probability the life span will be within 5 5,000 hours of the mean;
b) what must its lifetime be if it is to be categorized in the tallest 5%?
a) what is the probability the life span will be within 5 5,000 hours of the mean;
b) what must its lifetime be if it is to be categorized in the tallest 5%?
Correct answer:

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You need to know the following knowledge to solve this word math problem:
statisticsbasic operations and conceptsUnits of physical quantitiesGrade of the word problem
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