1)If we fail to reject (i.e., "accept") the null hypothesis, does this mean that we have proved it to be true beyond all doubt? Explain your answer.

No, it suggests that the null hypothesis is true only some of the time.

Yes, if we fail to reject the null we have found evidence that the null is true beyond all doubt.

No, it suggests that the evidence is not sufficient to merit rejecting the null hypothesis.

Yes, it suggests that the evidence is sufficient to merit rejecting the alternative hypothesis beyond all doubt.

2) Does a raw score less than the mean correspond to a positive or negative standard score? What about a raw score greater than the mean?

Raw scores below and above the mean will have negative standard scores.

Raw scores less than the mean will have positive standard scores; raw scores above the mean will have negative standard scores.

Raw scores less than the mean will have negative standard scores; raw scores above the mean will have positive standard scores.

Raw scores below and above the mean will have positive standard scores.

3) (a) What percentage of the area under the normal curve lies to the left of ?

%

(b) What percentage of the area under the normal curve lies between and + ?

%

(c) What percentage of the area under the normal curve lies between 3 and + 3?

%

4) Use the Student's t distribution to find tc for a 0.95 confidence level when the sample is 20. (Round your answer to three decimal places.)