Question

The average middle-distance runner at a local high school runs the mile in 4.5 minutes, with a standard deviation of 0.3 minute. Find the percentage of a runners that will run the mile in less than 4 minutes?
A. 45.22%
B. 15.87%
C. 7.15%
D. 4.75%

Answer 1

P(x<4)
=P((x-4.5)/0.3<(4-4.5)/0.3)
=P(z<-1.6666)=1-\[\phi\](1.6666)=0.1587

Answer 2

thanks!