1.

The confidence intervals for the population proportion are generally based on ________.

		the t distribution when the population standard deviation is not known
		the z distribution
		the t distribution
		the z distribution when the sample size is very small

2.

The difference between the two sample means 1 2 is an interval estimator of the difference between two population means 1 2.

True

False

3.

Excel does not have a special function that allows to calculate t values.

True

False

4.

The sampling distribution of is based on a normal distribution on samples of any size.

True

False

5.

A medical devices company wants to know the number of hours its MRI machines are used per day. A previous study found a standard deviation of four hours. How many MRI machines must the company find data for in order to have a margin of error of at most 0.5 hour when calculating a 98% confidence interval?

		425
		347
		346.26
		424.69