A civil engineer wishes to see whether the variation in sieve analysis of the 25 samples...
A civil engineer wishes to see whether the variation in sieve analysis of the 25 samples is less than the variance of the population. The variance of the sample is 199. Is there enough evidence to support the claim that the variation of the sieve analysis is less than the population variance (σ²=215) at α=0.01? Assume that the data in the laboratory are normally distributed.
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A civil engineer wishes to see whether the variation in sieve analysis of the 25 samples...
c. Find the critical t value(s) for ? .10 with n-18 for a two-tailed t test....
c. Find the critical t value(s) for ? .10 with n-18 for a two-tailed t test. 7. An instructor wishes to see whether the variation is scores of the 23 students in her class is less than the variance of the population. The variance of the class is 198. Is there enough evidence to support the claim that the variation of the students is less than the population variance (?2 225) at ? .05? Assume that the scores are normally...
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...
4. A market analysis wishes to see whether consumers have any preference between five different flavors...
4. A market analysis wishes to see whether consumers have any preference between five different flavors of chewing gum. A sample of 100 people provided the data below. Does enough evidence exist to reject the claim that no preference exists in the selection of chewing gum flavors? (10 points) Observed Expected 32 20 28 20 Frequency Mint Bubble Gum Strawberry Grape Orange 16 20 14 20 10 20 5. A medical researcher wishes to see whether the variance of the...
A researcher wishes to see if the average number of sick days a worker takes per...
A researcher wishes to see if the average number of sick days a worker takes per year is greater than 2.8. A random sample of 30 workers at a large department store had a mean of 3.1. The standard deviation of the population is 0.8. Is there enough evidence to support the researchers claim at α = 0.01?
5. A medical researcher wishes to see whether the variance of the heart rates (in beats...
5. A medical researcher wishes to see whether the variance of the heart rates (in beats per minute) of smokers is different from the variance of heart rates of people who do not smoke. Below is the data from two samples. Using a = 0.05, is there enough evidence to support the claim? (10 points) Smokers Non-Smokers n1 = 26 S12 = 32 n2= 18 s22 = 10
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...
Exercise 6. Weights. For a random sample of 38 students, the mean weight, x¯ = 176.8...
Exercise 6. Weights. For a random sample of 38 students, the mean weight, x¯ = 176.8 pounds. Assume that σ = 6.4 pounds and α = 0.05. A researcher claims that the population mean weight is greater than 175 pounds. Is there enough evidence to support the researcher’s claim? Assume the population is normally distributed.
A professor wishes to test a claim that the mean test score of her first class...
A professor wishes to test a claim that the mean test score of her first class is lower than the mean test score of her second class. A random sample of size 27 with a mean of 65.7 and a standard deviation of 5.4 is selected from her first class. A random sample of size 20 with a mean of 69.5 and a standard deviation of 12.1 is selected from her second class. Assume that test scores in both classes...
You wish to test the following claim ( H a ) at a significance level of...
You wish to test the following claim ( H a ) at a significance level of α = 0.02 . H o : μ = 51.6 H a : μ < 51.6 You believe the population is normally distributed and you know the population standard deviation is σ = 8.7 . You obtain a sample mean of M = 49.3 for a sample of size n = 51 . What is the test statistic for this sample? (Report answer accurate...
A photoconductor film is manufactured at a nominal thickness of 25 mils. The product engineer wishes...
A photoconductor film is manufactured at a nominal thickness of 25 mils. The product engineer wishes to increase the mean speed of the film, and believes that this can be achieved by reducing the thickness of the film to 20 mils. Eight samples of each film thickness are manufactured in a pilot production process, and the film speed (in microjoules per square inch) is measured. For the 25-mil film, the sample data result is j = 1.14 and = 0.11,...
c. Find the critical t value(s) for ? .10 with n-18 for a two-tailed t test. 7. An instructor wishes to see whether the variation is scores of the 23 students in her class is less than the variance of the population. The variance of the class is 198. Is there enough evidence to support the claim that the variation of the students is less than the population variance (?2 225) at ? .05? Assume that the scores are normally...
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...
4. A market analysis wishes to see whether consumers have any preference between five different flavors of chewing gum. A sample of 100 people provided the data below. Does enough evidence exist to reject the claim that no preference exists in the selection of chewing gum flavors? (10 points) Observed Expected 32 20 28 20 Frequency Mint Bubble Gum Strawberry Grape Orange 16 20 14 20 10 20 5. A medical researcher wishes to see whether the variance of the...
5. A medical researcher wishes to see whether the variance of the heart rates (in beats per minute) of smokers is different from the variance of heart rates of people who do not smoke. Below is the data from two samples. Using a = 0.05, is there enough evidence to support the claim? (10 points) Smokers Non-Smokers n1 = 26 S12 = 32 n2= 18 s22 = 10
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 photoconductor film is manufactured at a nominal thickness of 25 mils. The product engineer wishes to increase the mean speed of the film, and believes that this can be achieved by reducing the thickness of the film to 20 mils. Eight samples of each film thickness are manufactured in a pilot production process, and the film speed (in microjoules per square inch) is measured. For the 25-mil film, the sample data result is j = 1.14 and = 0.11,...
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