5. Imagine a researcher wanted to test the effect of the new drug on reducing blood pressure. In this study, there were 50 participants. The researcher measured the participants' blood pressure before and after the drug intake. If we want to compare the mean blood pressure from the two time periods with a two-tailed t test, how many degrees of freedom are there?

a. 49

b. 50

c. 99

d. 100

6. A researcher posed a null hypothesis that the average energy intake should be 2,200 calories per day in a certain community. He randomly sampled 30 people in that community and measured their energy intake. If he used a two-tailed t test and obtained a t value of 1.4, he can conclude___

a. The average energy intake in that community was bigger than 2,200 calories per day

b. The average energy intake in that community was smaller than 2,200 calories per day

c. The average energy intake in that community was not 2,200 calories per day

d. We cannot reject the null hypothesis