CHEN 3010
Applied Data Analysis
Fall 2002
Mid Term Test 2 – Version A
Open Book and Notes
4 digit number code:___________
Do not write your name anywhere on this test.
Instead write your four digit number code, chosen in your GradePostingPermission sheet.
Staple this question sheet to your answers written on blank paper provided.
Problem 1. (10 points) An engineer reports a 95 % confidence interval on the mean of 22
experimental measurements as: 12.14
≤
≤
μ
15.28.
Her boss, being a stricter analyst,
asks her to report a 99 % confidence interval.
Can you help her calculate it?
Problem 2. (30 points) The heat evolved in calories per gram of a mixing reaction is
normally distributed with the standard deviation of 2.
We wish to test H
0
:
μ
= 100 versus
H
1
:
μ
≠
100 with a sample of n = 9 measurements.
If the acceptance region is
determined to be 98.5
≤
≤
x
101.5, what is the type I error probability
α
?
What is the P value of
x
being equal to 102.5?
Find the type II error probability
β
for the case the true mean heat evolved is 103.
Problem 3. (30 points) The thickness of a plastic film (in mm) on a surface is thought to
be affected by the temperature at which the coating is applied.
Eleven surfaces are coated
at 125
o
F, resulting in a sample mean coating thickness of
1
x
= 1.179 and a sample
standard deviation of
s
1
= 0.088.
Nine surfaces are coated at 150
o
F, resulting in a sample
mean coating thickness of
2
x
= 1. 036 and a sample standard deviation of
s
2
= 0.124.
Do
the data support the claim that increasing the coating temperature would reduce the mean
coating thickness?
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 Spring '08
 KOMPALA,DH
 Statistics, Normal Distribution, Standard Deviation

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