Two independent plants manufacture a particular device. Suppose X = the life, in hours, of the...
Two independent plants manufacture a particular device. Suppose X = the life, in hours, of the device manufactured by Plant 1, and Y = the life, in hours, of the device manufactured at Plant 2.
Bill randomly samples 25 devices from Plant 1, and takes another random sample of 15 devices from Plant 2.
The standard deviations for each sample are 12.8 and 10.5 hours respectively.
If the population standard deviations are unknown but equal, compute an estimate of the common unknown population standard deviation.
Homework Answers
TOPIC:Pooled estimate of the population sd based on the sample from two populations.
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Two independent plants manufacture a particular device. Suppose
X = the life, in hours, of the...
An electronic device factory is studying the length of life of the electronic components they produced....
An electronic device factory is studying the length of life of the electronic components they produced. The manager selects two assembly lines and takes all samples on those two lines. He got a sample of 500 electronic components and records the length of life in the life test. From the sample he found the average length of life was 200,000 hours and that the standard deviation was 1,000 hours. He wants to find the confidence interval for the average length...
Forty refrigerators from two different models of a refrigerator manufacturer are compared to see if the...
Forty refrigerators from two different models of a refrigerator manufacturer are compared to see if the smaller model uses less energy than the larger model. The energy was measured in kilowatt hours per month (kwh/mo). From years of testing these models, it is known that the standard deviation of kwh/mo is 34 kwh/mo for the smaller model and 40 kwh/mo for the larger one. From this survey, the sample means and standard deviations are 125 and 34, and 90 and...
Two independent samples were selected from a population with mean µ=210 and standard deviation s=100. The...
Two independent samples were selected from a population with mean µ=210 and standard deviation s=100. The first sample, Group 1, included 49 patients, and the second sample, Group 2, had 64 patients. Now, we like to estimate the standard deviations of the means in Group 1 and Group 2. Which of the following answers are right? a Both standard deviations of the means in Group 1 and Group 2 are 100. b The standard deviations of the means in Group...
1. Twelve pairs of identical twins that were separated at birth are reunited at age 21....
1. Twelve pairs of identical twins that were separated at birth are reunited at age 21. Each twin is weighed. Of interest is if identical twins raised separately will weigh within 10 pounds of each other as young adults. The sample average difference was 12.1 pounds with a standard deviation of 3.4 pounds. If we conduct a hypothesis test, the distribution to use is ______________. a. Normal b. Binomial c. Student-t with df = 24 d. Student-t with df =...
16. In order to determine the life expectancy of a particular type of light bulb manufactured...
16. In order to determine the life expectancy of a particular type of light bulb manufactured by a lighting company, the corporate quality control officer randomly selected 10 bulbs from the pre-packaging section of the company's production line. The bulbs were subsequently tested in the quality control lab and the following data was recorded. Bulb Life (Hours). 3900 s ildedorg eris al terw.o 4200 weelido motus 4100 3800 4000 4300 3600 cools to Tenwo erTAL Tennib jot emotaus a. Calculate...
1. The life span of 100 W light bulbs manufactured by a particular company follows a...
1. The life span of 100 W light bulbs manufactured by a particular company follows a normal distribution with a standard deviation of 120 hours, and its average life time is guaranteed for a minimum of 800 hours. A delivery of 10,000 of light bulbs is sent to a wholesale store, and the quality control staff in the store randomly selected 50 bulbs to test the life time. The average life time of the sample is found out to be...
An electronic device factory is studying the length of life of the electronic components they produce....
An electronic device factory is studying the length of life of the electronic components they produce. The manager takes a random sample of 50 electronic components from the assembly line and records the length of life in the life test. From the sample he found the average length of life was 100,000 hours and that the standard deviation was 3,000 hours. He wants to find the confidence interval for the average length of life of the electronic components they produced....
Forty refrigerators from two different models of a refrigerator manufacturer are compared to see if the...
Forty refrigerators from two different models of a refrigerator manufacturer are compared to see if the smaller model uses less energy than the larger model. The energy was measured in kilowatt hours per month (kwh/mo). From years of testing these models, it is known that the standard deviation of kwh/mois 34 kwh/mo for the smaller model and 40 kwh/mo for the larger one. From this survey, the sample means and standard deviations are 125 and 34, and 90 and 40,...
1. Forty refrigerators from two different models of a refrigerator manufacturer are compared to see if...
1. Forty refrigerators from two different models of a refrigerator manufacturer are compared to see if the smaller model uses less energy than the larger model. The energy was measured in kilowatt hours per month (kwh/mo). From years of testing these models, it is known that the standard deviation of kwh/mo is 34 kwh/mo for the smaller model and 40 kwh/mo for the larger one. From this survey, the sample means and standard deviations are 125 and 34, and 90...
Independent random samples were selected from two quantitative populations, with sample sizes, means, and standard deviations...
Independent random samples were selected from two quantitative populations, with sample sizes, means, and standard deviations given below. n1 = n2 = 60 x1 = 125.3 x2 = 123.4 s1 = 5.7 s2 = 6.1 a) Construct a 95% confidence interval for the difference in the population means (μ1 − μ2). (Round your answers to two decimal places.) to b) Find a point estimate for the difference in the population means. c) Calculate the margin of error. (Round your answer...
Forty refrigerators from two different models of a refrigerator manufacturer are compared to see if the smaller model uses less energy than the larger model. The energy was measured in kilowatt hours per month (kwh/mo). From years of testing these models, it is known that the standard deviation of kwh/mo is 34 kwh/mo for the smaller model and 40 kwh/mo for the larger one. From this survey, the sample means and standard deviations are 125 and 34, and 90 and...
16. In order to determine the life expectancy of a particular type of light bulb manufactured by a lighting company, the corporate quality control officer randomly selected 10 bulbs from the pre-packaging section of the company's production line. The bulbs were subsequently tested in the quality control lab and the following data was recorded. Bulb Life (Hours). 3900 s ildedorg eris al terw.o 4200 weelido motus 4100 3800 4000 4300 3600 cools to Tenwo erTAL Tennib jot emotaus a. Calculate...
An electronic device factory is studying the length of life of the electronic components they produce. The manager takes a random sample of 50 electronic components from the assembly line and records the length of life in the life test. From the sample he found the average length of life was 100,000 hours and that the standard deviation was 3,000 hours. He wants to find the confidence interval for the average length of life of the electronic components they produced....
Forty refrigerators from two different models of a refrigerator manufacturer are compared to see if the smaller model uses less energy than the larger model. The energy was measured in kilowatt hours per month (kwh/mo). From years of testing these models, it is known that the standard deviation of kwh/mois 34 kwh/mo for the smaller model and 40 kwh/mo for the larger one. From this survey, the sample means and standard deviations are 125 and 34, and 90 and 40,...
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