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MIDTERM SOLUTIONS




Question 1
A) The data will be very discrete and right skewed. Answer C is not a sufficient reason to call a histogram non-normal. For instance, heights of adult males must be positive, but the histogram is quite normal looking.

Question 2
B) It's a t with 51 degrees of freedom and 0.975

Question 3
[2.4-2.009*1.9/sqrt(52),2.4+2.009*1.9/sqrt(52)]
The results are [1.87066,2.9293]

Question 4
Yes.

Question 5
The answers are B) and C). The fact is that everything changes, but a and d say that the s.d. and the interquartile range remain constant.

Question 6
The answers are B),C),D),E) and F). The only one that's not appropriate is the paired t-test.

Question 7
The answers are B),C),D),E) and F). Again the only not appropriate is the paired t-test.

Question 8
The answers are D), E) and F).

Question 9
The answer is C)

Question 10
The answer is A).

Question 11
The answers is the second. The 99% confidence is wider. If you want to be sure at the 99% you need to take more elements as possible answers, so the range of possible values will be more spread.

Question 12
It's false. It reflects the population.

Question 13
t*=1.761 distribution centered at 1 chance=0.23 Nearest answer: c=0.19

Question 14
It decreases.

Question 15
The median is about 38

Question 16
The interquartile range is about 20 units.

Question 17
You are supposed to choose the paired t-test, so there's strong evidence of a difference.

Question 18
p=0.0085

Question 19
paired-t-test

Question 20
.41

Question 21
[.13,.69]

Question 22
0.1 and 0.2 are considered correct answers for this problem.

Question 23
0.1 (2/20)

Question 24
Both a) and b) are considered valid answers for this problem.

Question 25
The answer is 0.0214.