7.5 Significance test using the t distribution. A test of a null hypothesis versus a two-sided alternative gives .

1. (a) The sample size is 23. Is the test result significant at the 5% level? Explain how you obtained your answer.

2. (b) The sample size is 9. Is the test result significant at the 5% level? Explain how you obtained your answer.

3. (c) Sketch the two distributions to illustrate your answers.