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The maintenance department at the main campus of a large state university
receives daily requests to replace fluorescent lightbulbs.
The distribution of the number of daily requests is bell-shaped
and has a mean of 64 and a standard deviation of 9.
Using the 68-95-99.7 rule, what is the approximate percentage
of lightbulb replacement requests numbering between 64 and 82?
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Notice that in this problem 82 is two standard deviation up from the mean of 64.
Since the normal distribution is symmetric, we may conclude that approximate percentage
of lightbulb replacement requests numbering between 64 and 82 is half of 95%-50%, i.e.
= 22.5%. ANSWER
Solved.