a) 95% confidence inetraval for the mean difference between the cognition test scores is C.I = (1.01, 4.99).
C.I = 3 + 1.974 × 1.0074
C.I = 3 + 1.989
C.I = (1.01, 4.99)
State the hypotheses. The first step is to state the null hypothesis and an alternative hypothesis.
Null hypothesis: µ1 – µ2 = 0
Alternative hypothesis: µ1 – µ2 ? 0
Note that these hypotheses constitute a two-tailed test.
Since the confidence interval deos not contain 0, hence we have to reject the null hypothesis.