Standard Deviation

Question

Suppose it is known that the weights of a certain group of individuals are approximately normally distributed with a mean of 140 pounds and a standard deviation of 25 pounds. What is the probability that a person picked at random from this group will weigh between 100 and 170 pounds?

Answer 1

You should calculate the z scores associated with x = 170 and x = 100 lbs.

Then use the Standard Normal Distribution table to find areas under curve associated with those respective z scores; the difference inb areas is the desired probability and all you have to do is to convert this to a probability by decimal point shift 2 places toward the right.