STA 2023 Work sheet #11

For each of the following, do a hypothesis test. Give H_o, H_a (label which is the claim), one-tail or two-tail, critical value, calculated value (round to the same number of places as the critical value from the table), decision (reject H_o or Fail to reject H_o), and a conclusion statement regarding the claim. DRAW EACH !!

1) In a 1997 survey of 880 U.S. households, 149 used e-mail. Test the claim that less than 20% of households used e-mail that year. Use a = .05.

2) In a recent presidential election, 611 voters were surveyed and 308 of them said they voted for the candidate that won. Use a = .04 to test the claim that among all voters 43% say they voted for the winning candidate.

3) In a study of check-out scanners, 1234 items were checked and 20 of them were found to be overcharges. Use a = .01 to test the claim that with scanners 1% of sales are overcharges.

4) One survey showed that among 785 randomly selected subjects who completed four years of college, 144 smoke. Use a = .02 to test the claim that the rate of smoking among those with 4 years of college is less than 27% for the general population.

5) An insurance company obtained a random sample of 850 drivers and finds 454 of them change CD’s while driving. Use a = .05 to test the claim that more than half of drivers change CD’s while driving.

6) 800 registered voters were asked if they favored a law that required a brain-damaged woman’s feeding tube to be re-inserted over the objection of her husband. 520 said they oppose the law, 184 favored the law and 96 were undecided or had no opinion. With a = .01, test the claim that more than 60% oppose this law. (Study results were published in Orlando Sentinel last Dec.)

7) 51 out of 79 students in college algebra in spring 2004 got A’s & B’s on Test #1 after having a practice test. Test the claim that the proportion increased if in fall 2003 without a practice test, it was 48%. (These are actual results from my classes.) Use a = .01.