Confidence Interval-Mean (Minimum Sample Size) 6.1

The standard IQ test has a mean of 97 and a standard deviation of 18. We want to be 95% certain that we are within 5 IQ points of the true mean. Determine the required sample size.

• 8

• 50

• 1

• 147

The standard IQ test has a mean of 95 and a standard deviation of 17. We want to be 95% certain that we are within 2 IQ points of the true mean. Determine the required sample size.

• 1

• 373

• 278

• 17

A nurse at a local hospital is interested in estimating the birth weight of infants. How large a sample must she select if she desires to be 99% confident that the true mean is within 3 ounces of the sample mean? The standard deviation of the birth weights is known to be 8 ounces.

• 47

• 6

• 48

• 7

A nurse at a local hospital is interested in estimating the birth weight of infants. How large a sample must she select if she desires to be 99% confident that the true mean is within 3 ounces of the sample mean? The standard deviation of the birth weights is known to be 6 ounces.

• 5

• 26

• 6

• 27

A nurse at a local hospital is interested in estimating the birth weight of infants. How large a sample must she select if she desires to be 99% confident that the true mean is within 3 ounces of the sample mean? The standard deviation of the birth weights is known to be 9 ounces.

• 60

• 8

• 7

• 59