Question

The maintenance department at the main campus of a large state university receives daily requests to replace fluorecent lightbulbs. The distribution of the number of daily requests is bell-shaped and has a mean of 65 and a standard deviation of 10. Using the 68-95-99.7 rule, what is the approximate percentage of lightbulb replacement requests numbering between 65 and 75?

Do not enter the percent symbol.

ans = %

Answer 1

Mean = 65

SD = 10

In statistics, the 68–95–99.7 rule, also known as the empirical rule, is a shorthand used to remember the percentage of values that lie within a band around the mean in a normal distribution with a width of two, four and six standard deviations, respectively; more accurately, 68.27%, 95.45% and 99.73% of the values lie in these ranges.

75 is one sd to right side from mean

68.27% lie on two sides

thus, 68.27/2 = 34.135 lies between 65 and 75