4. From the experiment described in problem 3, the researcher has the following results.: From the 50 mice who
received the non-steroid treatment, their mean skin irritation rating was 25.4 and their standard deviation was 5.8.
From the 50 mice who received the steroid treatment, their mean skin irritation rating was 24.8 and their standard
deviation was 4.8.
a. Construct a 90% confidence interval for the difference of means between the mice that did not receive the
steroids and the mice that did receive the steroids. Show all organized work as done in the videos and box your final
answer. Explain how you get the t-score for 90% CI.
[6pts]
b. Interpret the confidence interval in context of the problem.
[2pts]
c. Can we conclude that there is an improvement in the mice that had the steroid cream, compared to those that did
not? Clearly answer "yes" or "no" and then explain your answer. [2pts]
d. If there is an improvement, can we conclude that the steroid cream "caused" the skin to improve? Explain your
answer. (can we conclude a cause and effect?)
[2pts]
e. Were the criteria/conditions met to be sure that we can apply the Central Limit Theorem to this problem?
Clearly answer "yes" or "no", and explain your answer. [2pts]
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