Stats
posted by Anonymous on .
A loaf of bread is normally distributed with a mean of 22 ounces and a standard deviation of .5 ounces.
What is the probability that a loaf of bread is < 20.75

The first thing you have to do is find the z score. z=(20.7522)/.5 The z would be 2.5 Then, to find the probability, you can use your graphing calculator. Hit 2nd, then catalog, then go down to normalpdf. When that comes up, plug in 2.5 and it should give you a probability of .0175.
Hope that helps! 
If you don't have a graphing calculator, you can find table in the back of your statistics text labeled something like "areas under normal distribution" to find the probability.
I hope that helps a little more.