(19.) What is the proportion of the total area under the normal curve within plus and minus two standard deviations of the mean?

		68%
		99.7%
		34%
		95%

(20

A national manufacturer of unattached garages discovered that the distribution of the lengths of time it takes two construction workers to erect the Red Barn model is normally distributed with a mean of 32 hours and a standard deviation of 2 hours. What percent of the garages take between 30 and 34 hours to erect?

		16.29%
		76.71%
		3.14%
		34.13%

21

When all the items in a population have an equal chance of being selected for a sample, the process is called _________________.

		Simple random sampling
		z-score
		Sampling error
		Nonprobability sampling