Question

Times for an ambulance to respond to a medical emergency in a certain town are normally distributed with a mean of 450 seconds and a standard deviation of 50 seconds.

Suppose there are 160 emergencies in that town.

In about how many emergencies are the response times expected between 400 seconds and 500 seconds?



51

55 <my choice

80

109

Answer 1

http://davidmlane.com/hyperstat/z_table.html

Answer 2

how do I use that ?

Answer 3

use first choice, area from values

mean 450
sd 50

between 400 and 500

output is .6827 or 68% are between
well that is a little less thsan .7*160 = 112
so
109