Identify the choice that best completes the statement or answers the question.

1. Which of the following illustrates confidence level?

• 32.8
• 90%
• 90%-94%
• 30-39

2. In the past, the mean running time for a certain type of radio battery has been 9.6 hours. The manufacturer has introduced a change in the production method and wants to perform a hypothesis test to determine whether the mean running time has changed as a result. The null (H0) and alternative (H1) hypotheses are

• H0H0: 9.6 hours;HaHa: = 9.6 hours
• H0H0: > 9.6 hours;HaHa: > 9.6 hours
• H0H0: 9.6 hours;HaHa: = 9.6 hours
• None of the above

3. Regulations from the Environmental Protection Agency say that soil used in play areas should not have lead levels that exceed a400 400 parts per million(ppm). Before beginning construction at a new site, an agent will take a sample of soil and run a significance test on the mean lead level in the soil. If the mean lead level in the sample is significantly higher than400 400 ppm, then the soil is deemed unsafe and construction cannot continue. Here are the hypotheses for this test:

H0:400ppm(soilissafe)

Ha:>400ppm(soilisunsafe)

(where is the mean lead level in the soil at the new site).

What would be the consequence of a Type II error in this setting?

• Construction continues when the soil is actually safe.
• Construction continues when the soil is unsafe.
• Construction stops when the soil is actually safe.
• Construction stops when the soil is actually unsafe.

4. Which of the following decisions committed type I error?

• When we reject the null hypothesis, when in fact it is true.
• When we reject the null hypothesis, when in fact it is false.
• When we accept the null hypothesis, when in fact it is true.
• When we accept the null hypothesis, when in fact it is false.

5. The margin of error of the estimate is found by

• dividing