# Normal Curve Probability...

• March 23rd 2008, 12:30 PM
MathIsRelativelyUseless
Normal Curve Probability...
"A population is normally distributed with a mean of 25.8 and a standard deviation of 1.5. What is the probability that a randomly selected member of the population will have a measure greater than 28?"

And yet there are NO examples of this in the book nor in the online course.

Help?
• March 23rd 2008, 12:39 PM
CaptainBlack
Quote:

Originally Posted by MathIsRelativelyUseless
"A population is normally distributed with a mean of 25.8 and a standard deviation of 1.5. What is the probability that a randomly selected member of the population will have a measure greater than 28?"

And yet there are NO examples of this in the book nor in the online course.

Help?

Compute the z-score of 28 : $z=\frac{28-25.8}{1.5}=1.467$

Now look this up in a table of the cumulative standard normal to find: $P(z\le 1.467)$, and you want $P(z > 1.467)=1-P(z \le 1.467)$

RonL
• March 24th 2008, 10:20 AM
MathIsRelativelyUseless
Ah, thank you sir.