the weights of egge produced on a farm are normally distributed with a mean of 1.4 ounces and a stan

题目

the weights of egge produced on a farm are normally distributed with a mean of 1.4 ounces and a standard deviation of 0.4 ounces
1.what percent of the eggs weight at least 1 ounce?
2.how many of 1200 eggs are withiin 2 standard deviations of the mean?
3.to be a graded extra large,an egg must weight at least 2.2 ounces.what is the probability that an egg from this form will be graded extra large?

答案

1、84.13%
2、0.6826×1200=819.12≈819个
3、0.0228