Random sample
Second-year university students enrolled in a course were asked how many hours they spent doing homework in statistics. The data are listed below:
It is known that the population standard deviation is 9. The instructor recommends devoting hours per week for the duration of the 12-week semester. To determine whether the average student spent less than the recommended amount, fill in the requested information below.
The value of the standardized test statistic:
Note: For the next part, your answer should use interval notation and answer in the form of (-infty, x) or (x, infty), and an answer in the form of (a, b) should be expressed as (-infty, a) U (b, infty).
The rejection region for the standardized test statistic:
In a hypothesis test:
Reject H0
Reject H1
Do Not Reject H0
Do Not Reject H1
Randomly selected wristwatches are checked for accuracy, with positive errors representing watches that are ahead of the correct time and negative errors representing watches that are behind the correct time. The 45 values have a mean of 92 seconds and a standard deviation of 174 seconds. Use a 0.01 significance level to test the claim that the population mean is not 92 seconds.
The test statistic:
The p-value:
The final conclusion is:
There is sufficient evidence to support the claim that the mean is not equal to 92 seconds. There is not sufficient evidence to warrant rejection of the claim that the mean is equal to 92 seconds.
A certain automobile producer wants to estimate the number of miles per gallon achieved by a new car model. Suppose that a random sample of 40 cars achieves an average of 29.5 miles and assume the standard deviation is 2.5 miles. Now suppose the producer wants to test the hypothesis that the mean number of miles per gallon is 26.5 against the alternative hypothesis that it is not 26.5. Conduct the hypothesis test at a 0.05 significance level by giving the following:
Critical value:
Test statistic:
The final conclusion is:
We reject the null hypothesis that the mean is 26.5. We can reject the null hypothesis that the mean is 26.5 and accept that it is 26.5.
Golf course designers have become concerned that old courses are becoming obsolete since new technology has given golfers the ability to hit the ball farther. The designers are expecting that the average golfer can hit the ball more than 245 yards on average. Suppose a random sample of 10 golfers is chosen and their mean driving distance is 250.2 yards with a standard deviation of 48.3.
Conduct a hypothesis test when the following:
Null hypothesis: H0: μ = 245
Alternative hypothesis: H1: μ > 245
Test statistic:
The p-value:
If this was a two-tailed test, then the p-value would be: