Question

The seasonal output of a new experimental strain of pepper plants was carefully weighed. The mean weight per plant is 15.0 pounds, and the standard deviation of the normally distributed weights is 1.75 pounds. Of the 200 plants in the experiment, how many produced peppers weighing between 13 and 16 pounds?



a. 100

b. 118

c. 197

d. 53

Answer 1

I took the easy way out and used the Java normal distribution tool tool at
http://psych.colorado.edu/~mcclella/java/normal/accurateNormal.html

Enter the mean and the sigma and the higher and lower weight units and then click "enter". The probable fraction with weights in that interval is 0.5896
The answer (after multplying by 200 students) is 118

The same result could be obtained by using a table of the error function.