12. A manufacturer claims that the average tensile strength of thread A exceeds the average tensile...
12. A manufacturer claims that the average tensile strength of thread A exceeds the average tensile strength of thread B by at least 12kg. To test this claim, 50 pieces of each type of thread are tested under similar conditions. Type A had a sample average tensile strength of 86.7 kg with known population standard deviation of σA =6.28kg., while type B had a sample average tensile strength of 77.8 kg with a known population standard deviation of σB =5.61kg. Test the manufacturer’s claim at α =0.01.
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12. A manufacturer claims that the average tensile strength of
thread A exceeds the average tensile...
A bulb manufacturer claims that its compact fluorescent bulbs have an average of less than 3.5...
A bulb manufacturer claims that its compact fluorescent bulbs have an average of less than 3.5 mg of mercury. A sample of 25 bulbs showed a mean of 3.39 mg of mercury. The population standard deviation is 0.18 mg. Using α = 0.1, does the sample support the manufacturer’s claim? (use both methods)
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 manufacturer of auto engine oil claims that cars using their product can go an average...
A manufacturer of auto engine oil claims that cars using their product can go an average of 180 days without changing oil, with a standard deviation of 4 days. The distribution of the length of time between oil changes with this engine oil is known to be right-skewed. To test this claim a gas station owner takes a sample of 64 cars using this brand, and computes the sample mean. Assuming that the manufacturer’s claim is correct, which of the...
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...
The quality control manager of a tire company wishes to estimate the tensile strength of a...
The quality control manager of a tire company wishes to estimate the tensile strength of a standard size of rubber used to make a class of radial tires. A random sample of 50 pieces of rubber from different production batches is subjected to a stress test. The test measures the force needed to break the rubber in pounds. According to the sample results, the average pressure is 173 pounds. The podulation variance Is known to be 1225 pounds2. Construct a...
A fisherman claims that the mean breaking strength of his fishing line is 15 kg with...
A fisherman claims that the mean breaking strength of his fishing line is 15 kg with a standard deviation of 500 g. To test the hypothesis that u = 15 kg against the alternative that p < 15 kg, a random sample of 50 of his fishing lines will be tested. With the critical region is defined to be x < 14.9, find the probability of committing a type Il error for u = 14.9.
•Let’s say someone claims the average population size is 600 feet squared and the housing authority...
•Let’s say someone claims the average population size is 600 feet squared and the housing authority is skeptical of this and thinks this average is too small. It takes out a sample of n=81 and finds the averages of these samples to be 615. It is miraculously known that the standard deviation is σ= 150. •Let’s say a claim is now made the average population size is 654 feet and the housing authority says this figure is too big. Using...
(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 manufacturer of sprinkler systems used for re protection in once buildings claims that the true...
A manufacturer of sprinkler systems used for re protection in
once buildings claims that the true 130F. average system-activation
temperature is A sample of 9 systems when tested, yields a sample
131:08F. average activation temperature of Assume that the
distribution of activation times is normal 1:5F. with a population
standard deviation of a) Does the data contradict the claim at 0.01
level? Carry out a detailed test by writing the appropriate
hypotheses, rejection region and conclusion.
b) Find a 95%...
A company claims that their lightbulbs last an average of 400 days. To test this claim,...
A company claims that their lightbulbs last an average of 400 days. To test this claim, a random sample of 25 lightbulbs is tested and it is observed that they last for an average of 380 days with a standard deviation of 60 days. Part A) Assuming that the population of the time to failure of all lightbulbs is normally distributed, test the null hypothesis that the average life-length of their lightbulb is 400 days against the alternative that it...
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...
The quality control manager of a tire company wishes to estimate the tensile strength of a standard size of rubber used to make a class of radial tires. A random sample of 50 pieces of rubber from different production batches is subjected to a stress test. The test measures the force needed to break the rubber in pounds. According to the sample results, the average pressure is 173 pounds. The podulation variance Is known to be 1225 pounds2. Construct a...
A fisherman claims that the mean breaking strength of his fishing line is 15 kg with a standard deviation of 500 g. To test the hypothesis that u = 15 kg against the alternative that p < 15 kg, a random sample of 50 of his fishing lines will be tested. With the critical region is defined to be x < 14.9, find the probability of committing a type Il error for u = 14.9.
(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 manufacturer of sprinkler systems used for re protection in
once buildings claims that the true 130F. average system-activation
temperature is A sample of 9 systems when tested, yields a sample
131:08F. average activation temperature of Assume that the
distribution of activation times is normal 1:5F. with a population
standard deviation of a) Does the data contradict the claim at 0.01
level? Carry out a detailed test by writing the appropriate
hypotheses, rejection region and conclusion.
b) Find a 95%...
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