To determine the effect of drugs called beta-blockers on the heart rate of patients during surgery, the available subjects were randomly allocated into one of the two groups: 30 subjects in group 1 received a beta-blocker, and 30 subjects in group 2 received a placebo. Each subject's heart rate was recorded at a critical point during surgery with the following results. In group 1, the sample mean was 65.2 with the standard deviation of 7.8, and in group 2 the mean was 70.3, and the standard deviation was 8.3. Do not assume equal variances and adopt the conservative approach to the degrees of freedom.

1)For constructing the 95% confidence interval estimate of _1 -_2, what is the t* multiplier?

2.24

1.68

1.65

2.05

2)The 95% confidence interval estimate of _1 - _2 is -5.1

3.10

1.42

6.80

4.26