Question 467748
Twenty students randomly assigned to an experimental group receive an
instructional program; 30 in a control group do not. 
-------------------------------------
After 6 months, both groups are tested on their knowledge. 
The experimental group has a mean of 38 on the test (with an estimated population standard deviation of 3);
--------------- 
the control group has a mean of 35 (with an estimated population standard deviation of 5). 
--------------------
Using the .05 level, what should the experimenter conclude? 
(a) Use the steps of hypothesis testing,
Ho: u(c)-u(e) = 0
Ha: u(e)-u(c) > 0 (tests a claim that the instruction helped)
I ran a 2-Sample T test and got the following:
test statistic: t = 2.6482
p-value: 0.0109 
Conclusion: Since the p-value is less than 5%, reject Ho.
The test supports the claim.
----------------------------------------------
(b) sketch the distributions involved, and 
(c) explain your answer to someone who is familiar with the t test for a single sample but not with the t test for independent means
------
I'll leave b and c to you.
==============================
Cheers,
Stan H.