Question

The physical plant at the main campus of a large state university recieves daily requests to replace florecent lightbulbs. The distribution of the number of daily requests is bell-shaped and has a mean of 62 and a standard deviation of 8. Using the 68-95-99.7 rule, what is the approximate percentage of lightbulb replacement requests numbering between 54 and 62?

Answer 1

Solution :

Given that ,

mean = =62

standard deviation = = 8

P(54< x < 62) = P[(54 - 62) /8 < (x - ) / < (62 - 62 ) /8 )]

= P( -1< Z < 0)

= P(Z <-1)+P(Z <0 )

using empirical rule

=68%/2 + 0%/2

=34%+0%

=34%  

38%approximate percentage of lightbulb replacement requests numbering between 54 and 62