The tensile strength of stainless steel produced by a plant has been stable for a long...
The tensile strength of stainless steel produced by a plant has been stable for a long time with a mean of 72 kg/mm2 and a standard deviation of 2.15. A machine was recently adjusted and a sample of 50 items were taken to determine if the mean tensile strength has changed. The mean of this sample is 74.28. Assume that the standard deviation did not change because of the adjustment to the machine. Find a 95% confidence interval for the mean of tensile strength after the machine was adjusted. Does this data suggest that the tensile strength was changed after the adjustment?
Homework Answers
We need to construct the 95% confidence interval for the population mean μ. The following information is provided:
| Sample Mean | 74.28 |
| Population Standard Deviation | 2.15 |
| Sample Size | 50 |
The critical value for α=0.05 is z_c = 1.96 . The corresponding confidence interval is computed as shown below:
CI = (73.684, 74.876)
Since the interval does not contain 72 and even the lower limit is more than 72. hence the tensile strength has improved
Add Answer to:
The tensile strength of stainless steel produced by a plant has
been stable for a long...
Pr。Ыет 12. An engineer who is studying the tensile strength of a steel alloy intended for use in golf club shafts knows that tensile strength is approximately normally distributed. A random sample o...
Pr。Ыет 12. An engineer who is studying the tensile strength of a steel alloy intended for use in golf club shafts knows that tensile strength is approximately normally distributed. A random sample of 12 specimens has a mean tensile strength of 3250 psi and a sample standard deviation of 8-60 psi. a) Test the hypothesis that mean strength is 3500 psi. Use α-001. b) What is the smallest level of significance at which you coulji be willing to reject the...
(5 noints):Q1: Tensile strength tests were performed on two different grades of aluminum spars used in commercial a...
(5 noints):Q1: Tensile strength tests were performed on two different grades of aluminum spars used in commercial aircraft. From past experience with spar manufacturing process, the standard deviation of tensile strengths are assumed to be known. The data obtained are shown in table below. Find the 90% confidence interval on the difference in mean strength 1H2 Spar Sample Sample Mean Tensile Standard Deviation Grade size Strength (kg/mm) (kg/mm2) -87.6 n«10 ơ,-1.0 2 n2-12 o 1.5 74.5
(5 noints):Q1: Tensile strength...
A construction firm thinks that it is receiving 100 steel pipes with an average tensile strength...
A construction firm thinks that it is receiving 100 steel pipes with an average tensile strength of 10,000 pounds per square inch(lbs p.s.i.).This is the mean,μ.The size of the sample was n=100.The firm also knows that the population standard deviation,sigma,σ,is 400 p.s.i.The firm chooses a confidence interval of 95 %.This is equivalent to a level of significance,α,of 5 %(.05),where the null hypothesis is H0:μ0=10,000 and the alternative hypothesis is H1:μ0≠10,000.The company does not know that the actual, average tensile strength...
A civil engineer wishes to see if the tensile strength of the steel will change if...
A
civil engineer wishes to see if the tensile strength of the steel
will change if it is exposed to extreme temperature. Six
rebars were pretested, and then they were exposed to the extreme
heat 6-week period. The results are shown in the table. Can
it be concluded that tensile strength has been change at α=0.10.
Assume the variable is approximately normally distributed.
Determine also the confidence interval at 90%.
8. A civil engineer wishes to see if the tensile...
8. A civil engineer wishes to see if the tensile strength of the steel will change...
8. A civil engineer wishes to see if the tensile strength of the steel will change if it is exposed to extreme temperature. Six rebars were pretested, and then they were exposed to the extreme heat 6-week period The results are shown in the table. Can it be concluded that tensile strength has been changed at a 0.10? Assume the variable is approximately normally distributed. Determine also the confidence interval at 90% Subject Before (x.) 210 235 208 190 172...
A synthetic fiber used in manufacturing carpet has tensile strength that is normally distributed with mean...
A synthetic fiber used in manufacturing carpet has tensile strength that is normally distributed with mean 75.5 psi and standard deviation 3.5 psi. How is the standard deviation of the sample mean changed when the sample size is increased from n equals 10 to n equals 48 ? Round all intermediate calculations to four decimal places (e.g. 12.3456) and round the final answer to three decimal places (e.g. 98.768). The standard deviation is by psi.
A synthetic fiber used in manufacturing carpet has tensile strength that is normally distributed with mean...
A synthetic fiber used in manufacturing carpet has tensile strength that is normally distributed with mean 75.5 psi and standard deviation 3.5 psi. Suppose we measure the sample mean for n independent samples How is the variance of the sample mean changed when the sample size is increased from n-9 to n 36? What does this imply about the relationship between sample size and our estimate of the mean (sample mean here)?
Please be neat and clear so that I can follow through. Thank You and thumps up....
Please be neat and clear so that I can follow through. Thank You
and thumps up.
A sample of N The sample mean was found to be 36.2 ksi and the sample standard deviation was found to be 2.4 ksi. 4. 15 steel tensile specimens were taken and the yield strength of each measured Calculate a prediction interval, at 95 % confidence, for the yield strength value of the next sample. Calculate a 95 % confidence interval for the true...
In a sample of 100 steel wires the average breaking strength is 50 kN, with a...
In a sample of 100 steel wires the average breaking strength is 50 kN, with a standard deviation of 2 kN. How many wires must be sampled so that a 95% confidence interval specifies the mean breaking strength to within ±0.3 kN?
a synthetic fiber used in manufacturing carpet has tensile strength that is normally distributed usted with...
a synthetic fiber used in manufacturing carpet has tensile strength that is normally distributed usted with mean 75.5 psi and standard deviation 3.5 psi. find the probability that a random sample n=6 fiber specimens will have sample mean tensile strength that is between 75.25 and 75.75 psi
Pr。Ыет 12. An engineer who is studying the tensile strength of a steel alloy intended for use in golf club shafts knows that tensile strength is approximately normally distributed. A random sample of 12 specimens has a mean tensile strength of 3250 psi and a sample standard deviation of 8-60 psi. a) Test the hypothesis that mean strength is 3500 psi. Use α-001. b) What is the smallest level of significance at which you coulji be willing to reject the...
(5 noints):Q1: Tensile strength tests were performed on two different grades of aluminum spars used in commercial aircraft. From past experience with spar manufacturing process, the standard deviation of tensile strengths are assumed to be known. The data obtained are shown in table below. Find the 90% confidence interval on the difference in mean strength 1H2 Spar Sample Sample Mean Tensile Standard Deviation Grade size Strength (kg/mm) (kg/mm2) -87.6 n«10 ơ,-1.0 2 n2-12 o 1.5 74.5
(5 noints):Q1: Tensile strength...
A
civil engineer wishes to see if the tensile strength of the steel
will change if it is exposed to extreme temperature. Six
rebars were pretested, and then they were exposed to the extreme
heat 6-week period. The results are shown in the table. Can
it be concluded that tensile strength has been change at α=0.10.
Assume the variable is approximately normally distributed.
Determine also the confidence interval at 90%.
8. A civil engineer wishes to see if the tensile...
8. A civil engineer wishes to see if the tensile strength of the steel will change if it is exposed to extreme temperature. Six rebars were pretested, and then they were exposed to the extreme heat 6-week period The results are shown in the table. Can it be concluded that tensile strength has been changed at a 0.10? Assume the variable is approximately normally distributed. Determine also the confidence interval at 90% Subject Before (x.) 210 235 208 190 172...
A synthetic fiber used in manufacturing carpet has tensile strength that is normally distributed with mean 75.5 psi and standard deviation 3.5 psi. Suppose we measure the sample mean for n independent samples How is the variance of the sample mean changed when the sample size is increased from n-9 to n 36? What does this imply about the relationship between sample size and our estimate of the mean (sample mean here)?
Please be neat and clear so that I can follow through. Thank You
and thumps up.
A sample of N The sample mean was found to be 36.2 ksi and the sample standard deviation was found to be 2.4 ksi. 4. 15 steel tensile specimens were taken and the yield strength of each measured Calculate a prediction interval, at 95 % confidence, for the yield strength value of the next sample. Calculate a 95 % confidence interval for the true...
Most questions answered within 3 hours.
-
Where is the error in this code sequence?
String s1 = "Hello";
String s2 = "ello";...
asked 11 months ago -
Financial data for Joel de Paris, Inc., for last year
follow:
Joel de Paris, Inc.
Balance...
asked 11 months ago -
Consider this reaction:
Al2(SO4)3 (aq)+ BaCl3
(aq) Al2Cl6 (aq)- +
3BaSO4(s) . What is the...
asked 11 months ago -
Suppose that Savneet is considering increasing her
recent random sample from 20 car rentals to 40...
asked 11 months ago -
Trucks arrive at an unloading terminal at an average rate of 120
per hour.
Trucks arrive...
asked 11 months ago -
Why are methanol and ethanol completely soluble in water while
octanol is not very little soluble....
asked 11 months ago -
A facilities manager at a university reads in a research report
that the mean amount of...
asked 11 months ago -
When the CuSO4 is rehydrated by adding water to the anhydrous
compound, is this an endothermic...
asked 11 months ago -
A ray of sunlight is passing from diamond into crown glass; the
angle of incidence is...
asked 11 months ago -
A block of mass 0.249 kg is placed on top of a light, vertical
spring of...
asked 11 months ago -
how do the kidneys compensate in the presences of acidosis
a) trigger hyperventilate
b) reserve acid...
asked 11 months ago -
Question 501 pts
The rental rate of capital to the firm increases. Which of the
following...
asked 11 months ago