Assignment 7

1. What is the difference between the null hypothesis and the alternative hypothesis?

For question 2-4 below, identify the population parameter about which a claim is made, state the null hypothesis and the alternative hypothesis, and indicate whether the hypothesis test will be left-tailed, right-tailed, or two-tailed.

2. A consumer group claims that a new electric car gets less than the advertised 110 miles per charge.

3.The New York Department of Health claims the average stay in NYU Hospital after a surgery is greater than the national mean of 2 days.

4. A biologist claims that the actual proportion of male zebras in the wild is different from the accepted proportion of 50%.

5. What is a P-value for a hypothesis test?

The following table shows the probabilities of various numbers of heads in a random sample of 100 coin flips, assuming that coin is fair (ie, 50% heads/50% tails). Use this information for questions 6-8.

Number of heads among 100 coin flips	Probability
35 or fewer	.002
40 or fewer	.028
45 or fewer	.184
48 or fewer	.38

6. The result of 100 coin flips was 48 heads. What is the P-value for the result? Is this significant at the .05 level?

7. The result of 100 coin flips was 35 heads. What is the P-value for the result? Is this significant at the .05 level?

8. The result of 100 coin flips was 40 heads. What is the P-value for the result? Is this significant at the .05 level?

9. Do criminal trials ever prove a defendant's innocence? Why?

10. What is the equivalent of failing to reject the null hypothesis in a criminal trial?