Practice Final – Winter 2009
These questions are mostly concerned with the latter part of the course.
The final exam will be weighted
so that about half is on just the topics covered since the last midterm (or around that time, I include using
the central limit theorem in this 'last part' of the course) and half on the entire course.
Question 1.
Suppose that we are interested in estimating the mean of some distribution.
a)
Show why more observations (if they are randomly obtained) gives us a better idea of what the true
mean of the generating distribution is.
b) Suppose we have two estimates from random samples, one from a sample of size equal to 100 and
another with size 1000.
Which estimated mean is closer to the true mean? Explain.
Question 2.
We want to examine if
the average IQ of students in a particular class is equal to 100.
We
estimate that the average IQ of a subset of 36 of the students is 95.
The standard deviation is equal to 25
(assume this was known).
Calculate the probability that if our guess of 100 is actually correct we get a
sample average of
95 or less.
Make sure you justify any assumptions made in obtaining your answer.
Q3. The following study on survival rates when treated after a heart attack was reported in the news last
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 Spring '09
 ichigaara
 Normal Distribution, Probability theory, Randomness, heart attack

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