Suppose that the weights of 5400 registered female Labrador retrievers in the United States are distributed normally with a mean of 62.5 lb and a standard deviation of 2.5 lb.

Approximately how many of the Labrador retrievers weigh less than 65 lb?

We are given in the problem the data on the number of respondents, the mean and the standard deviation. In this problem, we find first the z-score through z = (65-62.5) / 2.5 = 1. We find next the probability of this z-score then multiply the probability to the number of respondents. That is the answer