STAT307 Quiz #2 (21 points) Form A
Score: _______________ Name: __________________________
Student id #:______________________
STAT307 Section:__________________
Write out the following statement by hand in the lines below:
On my honor as a Colorado State University student, I have neither given nor received any unauthorized aid on this exam.
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
Signature: _____________________________________
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There are 21 points total.
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The quiz is closed book, yet open to one note sheet plus Z- and T-tables.
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A calculator may be used for BASIC ARITHMETIC ONLY.
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No sharing of calculators is allowed.
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Show all of your work.
Charlie Vollmer
October 9 th , 2015 STAT307-003 Fall, 2015 Quiz 2
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STAT307 Quiz #2 (21 points) Form A
Use the information in the following setting to answer questions 1 and 2
One of the variables collected in the North Carolina Birth Registry data is pounds gained during pregnancy. According to data from the entire registry for 2001, the number of pounds gained during pregnancy was approximately normally distributed with a mean of 30.23 and a standard deviation of 13.85 pounds.
1) What is the probability that a randomly selected mother in North Carolina in 2001 gained more than 15 pounds? [3 pt]
2) What is the probability that a randomly selected mother in North Carolina in 2001 gained exactly 24 pounds? [3 pt]
Charlie Vollmer
October 9 th , 2015 STAT307-003 Fall, 2015 Quiz 2
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STAT307 Quiz #2 (21 points) Form A
Use the information in the following setting to answer questions 3 and 4
Researchers sampled 15 obstetrics and gynecology interns at the University of Colorado
Health Sciences Center in order to assess the competence of such interns in performing clinical breast examinations. One of the baseline measurements was the number of such examinations performed. The sample provided a mean of 25.9 examinations and a standard deviation of 9.47 examinations. The researchers wish to find a 95% confidence interval for the true mean number of examinations performed by all obstetrics and gynecology interns.
3) Find the margin of error for the 95% confidence interval. [3 pt]
4) Find the 95% confidence interval for the true mean number of examinations performed by all obstetrics and gynecology interns. [3 pt]
5) A 95% confidence interval for m
means that a. population means are random, and 95% of the possible population means, m
, will be included in the interval. b. sample means are random, and 95% of the possible sample means x will be included in the interval. c. confidence intervals are random, and 95% of the confidence intervals generated will include the true mean m
. d. confidence intervals are random, and 95% of the confidence intervals generated will include the sample mean x .
[3 pt]
Charlie Vollmer
October 9 th , 2015 STAT307-003 Fall, 2015 Quiz 2
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STAT307 Quiz #2 (21 points) Form A
6) A simple random sample of 1,000 persons is taken to estimate the percentage of
Democrats in a large population. It turns out that 543 of the people in the sample are
Democrats. The sample percentage is (543/1,000) x 100% = 54.3%. The Margin of
Error for the sample percentage of Democrats is figured as 3.2%.
There is about a 95% chance for the percentage of Democrats in the population to be in the range 54.3% ± 3.2%.
Circle: True or False [3 pt]
7) (6 cont…) If another survey organization takes a simple random sample of 1,000 persons, there is about a 95% chance that the percentage of Democrats in their samp le will be in the range 54.3% ± 3.2%.
Circle: True or False [3 pt]
Extra Credit
8) Suppose the following is a graphical representation of a probability density function.
Find a. [3 pt]
Charlie Vollmer
October 9 th , 2015 STAT307-003 Fall, 2015 Quiz 2
Page 4 of 4