The weights of cockroaches living in a typical college dorm are approximately distributed with a mean of 80 grams and a standard deviation of 4 grams.

Question

The percentage of cockroaches weighing between 71 grams and 80 grams is about?

Answer 1

z= (x-µ)/σ = (71-80)/4 =-2.25 with corresponding p-value = 0.0122

(80-80)/4 =0 with corresponding  p-value =0.5

so P(71<x<80) = 0.5-0.0122=0.4878 =48.78%