Math 243 Exam-like Questions

Which answer incorrectly describes the graph?

• Both distributions have the same mean.

• Both distributions have the same mode.

• Both distributions have the same standard deviation.

• Both distributions have the same mode.

A test is H0: µ=µ0 against Ha: µ>µ0 gives a z-statistic of z=1.85. The result is:

• Significant at both α=.05 and α=.01

• Significant at α=.05 but not α=.01

• Significant at α=.01 but not α=.05

• Not significant at either α=.05 or α=.01

Test Ho: µ=10 against Ha: µ<10 based on an SRS of 20 observations. The test statistic is t=-2.25. The degrees of freedom for this statistic is:

• 18

• 20

• 21

• 19

The 2005 National Assessment of Educational Progress gave a mathematics test to a random sample of eight-graders in Texas. The mean score was 281 out of 500. To give a confidence interval for the mean score of all Texas eight-graders, you would use:

• the one-sample t interval

• the two-sample t interval

• the matched-pairs t test

• the one-sided t test

You use software to carry out a test of significance. The program tells you that the p-value=0.031. This means:

• the probability that the null hypothesis is true is 0.031

• the probability that the alternative hypothesis is true is 0.031

• the value of the test statistic is 0.031

• a test statistic as extreme as these data would happen with probability 0.031 if the null hypothesis were true