# Samples, Populations, and Normal Distributions

1. Based on a large number of recorded birth weights, the mean birth weight of babies born in the general population of the US is established at approximately 115 ounces. A sample of 50 birth weights was drawn randomly from the population consisting of all babies born to mothers who consumed two or more drinks per day during their pregnancy. The sample yielded a mean of 103 ounces and a sample standard deviation of 35 ounces. Does this sample deviate from the mean of the general population by chance alone or do the mothers who drink during pregnancy tend to have smaller babies?

2. A Canadian wildlife biologist drew a sample of 30 wide mouth bass from a small lake in northern Ontario. She measure the length of each member of the sample obtaining the following in centimeters:

30 40 60 49 26 40 57 45 61 57 66 58 48 55 43 49 25 62 36 5158 71 49 56 46 51 49

70 55 36

Compute the 95% and the 99% confidence intervals for the mean length of bass population.

3. The mean cholesterol level of a large population of men in the 50 to 60 age group is 190 milligrams per 100 milliliters of blood. The standard deviation of the population is 25 milligrams per 100 milliliters. Assume the measurements are distributed approximately normally.

A) What percent of the pop. Has cholesterol levels greater than 220 milligrams?

B) What percent has less than 140 milligrams

C) What percent has between 200 and 250 milligrams

D) What percent has between 180 and 210 milligrams

E) What percent has between 135 and 175

#### Solution Summary

This solution provides calculations in Excel for questions regarding samples, populations, and normal distributions.