EXAM 3
1.
An article in a recent medical journal pointed out that better nutrition has increased the mean weight of adult men in the United States to 175 pounds. The director of a weight control institute felt the figure was too high for the males in the region served by her institute. A sample of 45 men yielded average weight of 168.7 pounds. Assume that the population standard deviation of the weight of the adult men in this region is 25.9 pounds.a. State the null and alternative hypotheses.
b.
Carry out the test and give the P-value. Report your conclusion.
p-value provide some evidence against the null hypothesis.
c. Is the result significant at the 5% level (
)?
p-value is not smaller than the significance level of 0.05. Therefore, we fail to reject the null hypothesis. The test is not significant.
2.
A customer's group sampled 49 different stores in the city and found that the average price of a particular model and brand of washing machine was $522.85 with a population standard deviation of $29.55.a. Find a 95% confidence interval for the average price of this particular washing machine.
b.
How many observations must be averaged to get a margin of error of
with 95% confidence?
3. A national magazine claims that the average college student watches less television than the general public. The national average is 29.4 hours per week. A sample of 30 college students has a mean of 27 hours and a sample standard deviation of 2 hours.
a. Construct a 99% confidence interval for the mean length of time a college student watches television.
b.
Test the hypothesis that the average college student watches less television than the general public. Use a=0.01.
a
=0.01
Reject the null hypothesis. There is a statistical evidence that college students watch TV less than the public.