4) A study was done using a treatment group and a placebo group. The results are shown in the table. Assume that the two samples are independent simple random samples selected from normally distributed populations, and do not assume that the population standard deviations are equal. Complete parts (a) and (b) below. Use a

0.05 significance level for both parts.

Treatment/ Placebo

u U1 u2

n 30 38

x 2.33 2.65

s 0.67 0.97

A: The null and alternative hypotheses:

Ho: u1= u2

H1: u1 u2

B: The test statistic t is:

_{(round to two decimal places as needed.)}