There are two samples (new drug vs. old therapy) in a clinical research. Research data indicated that new drug sample mean is =238. The old therapy sample mean is = 250. The new drug sample standard deviation is s1=25 while the old therapy sample s2=22.6. Two sample sizes are: new drug sample n1=30 and old therapy sample n2=100. Please calculate the pooled variance: Group of answer choices 536.64 661 268.3 161