For a normal curve,if the mean is 20 minutes and the standard deviation is 5 minutes,then the area between 11 and 19 minutes is:
A) 0.4641.
B) 0.0359.
C) 0.3848.
D) 0.8848.
E) 0.9641.

Question

Quizplus · Accepted Answer

We need to find the area between 11 and 19 minutes which is equivalent to finding the area to the left of 19 minus the area to the left of 11.

Using the z-score formula, we get:

z(19) = (19-20)/5 = -0.2 
z(11) = (11-20)/5 = -1.8

Using a standard normal table (or calculator), we can find the probabilities for each z-score:

P(Z < -0.2) = 0.4207 
P(Z < -1.8) = 0.0359

Therefore, the area between 11 and 19 is:

P(-1.8 < Z < -0.2) = P(Z < -0.2) - P(Z < -1.8) 
= 0.4207 - 0.0359 
= 0.3848

So, the answer is C.

For a Normal Curve,if the Mean Is 20 Minutes and the Standard