1- A researcher estimates that the average height of buildings of 30 or more stories in a large city is at least 700 feet. A random sample of 10 buildings is selected, and the heights in feet are shown.

450 510 830 725 615 520 530 630 610 580.

At a = 0.025, is there enough evidence to reject the claim?

2- A report by the NCAA states that 55% of football injuries occur during practices.

A head trainer claims that this is too high for this conference, so he randomly selects 35 injuries and finds that 14 occurred during practices.

Is his claim correct, at a = 0.05?

3- A sample of heights (in feet) of active volcanoes in North America, outside of Alaska,

is listed below.

10,672 8160 11,724 10,654 13,163 8320

At a = 0.05, is there sufficient evidence that the standard deviation in heights of volcanoes outside of Alaska is less than the standard deviation in heights of Alaska volcanoes, which is 2385 feet?

4- The average 1-year-old (both gender) is 29 inches tall. A random sample of 30 one-year-olds in a large day care franchise is selected and the average is shown as 29.5 inches.

At a = 0.01, can it be concluded that the average height differs from 29 inches? Assume s = 2.61.

5- A sample of 42 chemists from Washington state shows an average salary of $39,420 with a standard deviation of $1659, while a sample of 36 chemists from New Mexico has an average salary of $30,215 with a standard deviation of $4116.

a- Is there a significant difference between the two states in chemists' salaries at = 0.02?

b- Find the 98% confidence interval of the difference in the means.