Question

1. The National Highway Traffic Safety Administration indicated that 284 people died between 1990 and 2007 as a result of an injury caused by an airbag. Newer airbags open at a speed proportional to the speed of an impact. Older models open at a constant speed, up to 200mph, equal to the force of a heavyweight knockout punch. A random sample of 40 older-model airbags was obtained and tested. The average opening speed for each older-model airbag was 173.88. Airbag opening speed is normally distributed with s =10 mph.

Compute a 90% confidence interval for the mean opening speed in older-model airbags. Be sure to check all necessary assumptions and conditions, and interpret your interval within the context of the problem.

2

TRUE/FALSE    Please correct any false statements.

1. A confidence interval widens as its confidence level increases.                                             _____

2. A confidence interval widens as its sample size increases.                                                        _____

3. Confidence levels refer to the probability that the interval will capture the true parameter       _____

in repeated samples. They are not the likelihood that particular intervals contain the true parameter.                                                                                               

4. One-sided hypothesis tests are used when we are stating that a                                              _____

parameter is larger than the null hypothesis value.                                                              

5. When the P-value > a, there is enough evidence to reject the null hypothesis.                        _____

6. Not having enough evidence to reject the null hypothesis and concluding

    that the null hypothesis is true are equivalent statements.                                                   _____

Answer 1