utpb.instructure.com/courses/6892/quizzes/25061/take D Question 3 1.5 pts A biop

Question

utpb.instructure.com/courses/6892/quizzes/25061/take D Question 3 1.5 pts A biopsychologist is studying the role of the role of marijuana (THC) on aggression in rats. Specifically, the researcher asserts that the influence of large doses of marijuana will make rats more aggressive. Twenty two rats are randomly assigned to one of two groups. The active ingredient in marijuana is called delta-9 THC. One group of 11 rats serves as a control group and receives a placebo (via injection). A second group of 11 different rats receives a large dose of delta-9 THC via injection. These rats have not been paired up on any trait. Then the researcher tests the animals by recording the number of aggressive responses each of the rats display in a 30 minute test period one hour after the rats were injected. The data are presented below, and represent the number of aggressive responses per rat in each group. X2 Placebo Large dose of delta-9 THC Group 17 15 18 14 12 12 8

Explanation / Answer

Here the mean and standard deviation of control group and placebo group is given below.

Here pooled standard deviation sp = sqrt (s12 + s22)/2] = sqrt [(3.10132 + 2.98182)/2] = 3.042

so,

Test statitic

t = (x1 - x2)/[sp * sqrt(1/n1 + 1/n2)] = (16.2727 - 12.0910)/[3.042 * sqrt(1/11 + 1/11)] = 4.1817/1.2971 = 3.23

Here option C seems most good as p < 0.05 here also as t(critical) = 1.7247

X1 X2 17 9 15 12 18 11 14 12 20 15 11 12 15 10 20 19 18 14 19 9 12 10 Mean 16.2727 12.0910 Std. Dev. 3.1013 2.9818

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