Test 2A

Use the information in the previous problem. (The heights of American men aged 18 to 24 are approximately Normally distributed with a mean of 68 inches and a standard deviation of 2.5 inches. Only about 5% of young men have heights outside the range) About what percentage of the men are over 70.5 inches tall?

16%

The heights of American men aged 18 to 24 are approximately Normally distributed with a mean of 68 inches and a standard deviation of 2.5 inches. Only about 5% of young men have heights outside the range:

63 inches to 73 inches.

Which of the following properties is true for all Normal density curves? i. The are symmetric ii. The curve reaches its peak at the mean. iii. 95% of the area under the curve is within one standard deviation of the mean

i and ii only

A fire department in a rural county reports that its response time to fires is approximately Normally distributed with a mean of 22 minutes and a standard deviation of 11.9 minutes. Approximately what proportion of their response times is over 30 minutes?

0.25

The area under the standard Normal curve corresponding to -0.3 < Z < 1.6 is

0.5631

The cumulative relative frequency graph at right shows the distribution of lengths (in centimeters) of fingerlings at a fish hatchery. The interquartile range for this distribution is approximately:

1.2 centimeters

For the density curve shown to the right, which statement is true?

The area under the curve between 0 and 1 is 1

The distribution of the time it takes for different people to solve a certain crossword puzzle is strongly skewed to the right, with a mean of 30 minutes and a standard deviation of 15 minutes. The distribution of z-scores for those times is

Skewed to the right, with mean 0 and standard deviation 1

The graph at the right is a normal probability plot for the amount of rainfall (in acre-feet) obtained from 26 randomly selected clouds that were seeded with silver oxide. Which of the following statements about the shape of the rainfall distribution is true?

The distribution is skewed right

For the density curve shown in problem 3, which statement is true

the mean is less than the median