Question

the number or interviews recieved by a college graduating class is normally distributed with a mean of 8 interviews , standard deviation of 2 interviews

15% of all graduates recieve more than how many interviews?

Answer 1

Solution:

Given: the number or interviews received by a college graduating class is normally distributed with a mean of 8 interviews , standard deviation of 2 interviews.

That is: X ~ Normal .

We have to find x = Number of  interviews such that: 15% of all graduates receive more than x interviews.

That is find x value such that:

P( X > x ) =15%

P( X > x ) =0.1500

Thus find z value such that:

P( Z > z ) =0.1500

that is :

P(Z < z ) =1 - P( Z> z )

P(Z < z ) =1 - 0.1500

P(Z < z ) = 0.8500

Look in z  table for Area = 0.8500 or its closest area and find corresponding z value.

Area 0.8508 is closest to 0.8500 and it corresponds to 1.0 and 0.04

that is  z = 1.04

Now use following formula to find x value:

Thus 15% of all graduates receive more than 10  interviews.