Question

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

Answer 1

I believe the normal distribution is symmetrical above and below

the mean.  That tells us that in this kind of distribution, the mean

and the median are the same number ... 50% of the population

is below it, and 50% is above it.

So if the female Labs' weight actually follows a 'normal' distribution

with a mean of 62.5 lbs, then 2,700 of them weigh more than 62.5 lbs

and 2,700 of them weigh less than that. 

The standard deviation doesn't matter.