Jim Tree pays for shipping on the basis of weight. He knows weight is normally distributed so he can use the standard normal distribution. He decides to weigh 1,000 randomly trees in his shipment. Next, he calculates the mean and
standard deviation of their weights. He finds the mean is 30 lbs and the standard deviation is 10 lbs. Now, Jim uses the
normal distribution table to calculate the number of trees in each segment of the distribution.
Standard Deviation
% from table No. of trees out of 1,000
O to +1 (30 to 40 lbs)
34%
+1 to +2 (40 to 50 lbs) 13.7%
137
+2 to +3 (50 to 60 lbs) 2.3%
Totals
50%
500