Download Classwork due 3/7/2017

Community College of Denver
Course: MAT135 –Statistics
Instructor: Vikki French
[email protected]
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Classwork due 3/7/2017
Normal vs Non-normal Distributions
1) Which is positively skewed?
2) Which is negatively skewed?
3) Which is platykurtic?
4) Which is leptokurtic?
Sampling Distributions
5) From which of these would you expect the distribution of the sample means to be
normal?
Original population normal
Samples taken of size 10
Sample taken of size 50
Highly skewed population
Graphs of x̄
6) What is the best estimate we have for the unknown population mean µ?
7) Graph of likely values for µ:
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Estimation
Suppose we have a population of x̄s from samples of size 49
The mean of the x̄s is 150
The standard deviation is 56
8) Can we assume the population of x̄s forms a normal distribution?
9) What is our best estimate of the original population mean?
10) What is our best estimate of the original population standard deviation?
11) What is our estimate of the standard error?
12) What will be the normal curve
for the x̄s:
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13) What is the probability that the true population mean is between 142 and 158?
14) What is the probability that the true population mean is 150?
15) What is the range of values that would ensure with 95% probability that we include the
mean?
16) What is the probability the true p lies between 130 and 145?