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 59 and a standard deviation of 3. Using the 68-95-99.7 rule, what is the approximate percentage of lightbulb replacement requests numbering between 50 and 59?

Answer 1

Solution :

Given that ,

mean = =59

standard deviation = = 3

P(50< x < 59) = P[(50- 59) /3 < (x - ) / < (59 - 59 ) /3 )]

= P( -3< Z < 0)

= P(Z <0)+P(Z <-3 )

using empirical rule

=0%/2 + 99.7%/2

=0%+49.85%

=49.85%