Question
In: Statistics and Probability
A sample of n = 20 specimens of cold-processed steel bars was taken to measure their...
A sample of n = 20 specimens of cold-processed steel bars was taken to measure their strength. The average resistance of the sample was 29.8 ksi, while the sample standard deviation was 4.0 ksi. A second sample consisting of 25 galvanized steel bars was also evaluated. The average resistance for this second sample was 34.7 ksi. and the sample standard deviation was 5.0 ksi.
Assuming that the data comes from normal distributions and that the variances cannot be assumed to be the same:
a. Determine if there is evidence to conclude that the means of the two populations are different. Express your conclusion clearly _ clearly state the hypotheses you are testing, the areas of acceptance and rejection, the test statistician and EXPRESS your conclusion in complete sentence
b. Calculate the p-value. Explain how to use the p-value to conclude
c. Would it have been reasonable to assume equal variances?
Solutions
orchestra answered 1 year agoRelated Solutions
A sample of n = 20 specimens of cold-processed steel bars was taken to measure their...
A sample of n = 20 specimens of cold-processed steel bars was
taken to measure their strength. The average resistance of the
sample was 29.8 ksi, while the sample standard deviation was 4.0
ksi. A second sample consisting of 25 galvanized steel bars was
also evaluated. The average resistance for this second sample was
34.7 ksi. and the sample standard deviation was 5.0 ksi. Assuming
that the data comes from normal distributions and that the
variances cannot be assumed to...
A sample of n = 20 specimens of cold-processed steel bars was taken to measure their...
A sample of n = 20 specimens of cold-processed steel bars was
taken to measure their strength. The average resistance of the
sample was 29.8 ksi, while the sample standard deviation was 4.0
ksi. A second sample consisting of 25 galvanized steel bars was
also evaluated. The average resistance for this second sample was
34.7 ksi. and the sample standard deviation was 5.0 ksi.
Assuming that the data comes from normal distributions and that
the variances cannot be assumed to...
Analysis of a random sample of 15 specimens of cold-rolled steel to determine yield strengths resulted...
Analysis of a random sample of 15 specimens of cold-rolled steel
to determine yield strengths resulted in a sample mean strength of
29. 8 and a standard deviation of 4. 0. A second random sample of
14 specimens of galvanized steel resulted in a sample mean of 32. 7
and a standard deviation of 5. 0. Does the data indicate that the
true mean yield strengths for the two given populations
(cold-rolled or galvanized) are different? Test at a= 0....
Two machines are supposed to be producing steel bars of approximately the same length. A sample of...
Two machines are supposed to be producing steel bars of
approximately the same length. A sample of 35 bars from
one machine has an average length of 37.013 inches, with a standard
deviation of 0.095 inches. For 38 bars produced by the
other machine, the corresponding figures are 36.074 inches and
0.032 inches. Using a 0.05 level of significance and
assuming equal population standard deviations, can we conclude that
the machines are not different from each
other? Construct and interpret the 95 percent confidence...
A sample of 62 households was taken to measure the amount of discarded plastics. The sample...
A sample of 62 households was taken to
measure the amount of discarded plastics. The sample mean was 1.911
lbs. and the standard deviation was 1.065 lbs. test the hypothesis
test that the amount of discarded plastic per household was 1.8
lbs.
State the null and alternative hypothesis (3 Points)
Test Statistics (2 points)
P-value approach ( 2 points)
Conclusion: (3 points)
A steam contains 55 mol% n-pentane, 25 mol%n-hexane and 20 mole% n-heptane is to be processed...
A steam contains 55 mol% n-pentane, 25 mol%n-hexane and 20 mole%
n-heptane is to be processed at 69°C. The following data are
available. Data at 69°C P(pentane)vap.= 2.755 bar,
P(hexane)vap.=1.021 bar and P(heptane) vap.=0.390 bar. a) What is
the bubble point pressure of this mixture and vapor composition
that results? b) What are the dew point of this mixture and the
liquid composition that results?
An Izod impact test was performed on 20 specimens of PVC pipe. The sample mean is...
An Izod impact test was performed on 20 specimens of PVC pipe.
The sample mean is x Overscript bar EndScripts equals 1.44 and the
sample standard deviation is s = 0.27. Find a 99% lower confidence
bound on the true Izod impact strength. Assume the data are
normally distributed. Round your answer to 3 decimal places.
less-than-or-equal-to
An Izod Impact Test was performed on 20 specimens of PVC pipe. The sample mean is...
An Izod Impact Test was performed on 20 specimens of PVC pipe.
The sample mean is ? = 1.25, and the sample ??? ??????? ? standard
deviation is ? = 0.25. You need to test if the true mean Izod
Impact Strength is less than 1.5.
a.Write down the Null and Alternative Hypotheses to be
tested
b.What is the appropriate type of statistical test? Explain.
c.Construct a 95% ?????????? ???????? and test the Hypotheses.
Clearly interpret the test result.
d.Test...
In a sample of 59 water specimens taken from a construction site, 22 contained detectable levels...
In a sample of 59 water specimens taken from a construction
site, 22 contained detectable levels of lead. What is the upper
bound for the 90% confidence interval for the proportion of water
specimens that contain detectable levels of lead. Round to three
decimal places (for example: 0.419). Write only a number as your
answer.
Contaminated water: In a sample of 42 water specimens taken from a construction site, 26 contained...
Contaminated water: In a sample of
42
water specimens taken from a construction site,
26
contained detectable levels of lead.
Part 1 of 3
Your Answer is correct
(a) Construct a
90%
confidence interval for the proportion of water specimens that
contain detectable levels of lead. Round the answer to at least
three decimal places.
A
90%
confidence interval for the proportion of water specimens that
contain detectable levels of lead is
0.497<<p0.743
.
Part: 1 / 3
1 of...
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