"An electrical firm produces light bulbs that have a length of life that is approximately normally distributed with a mean of 660hours and a population standard deviation of 23 hours. A new version of light bulbs is being produced and is assumed to be betterthan the previous version. To test this claim, a random sample of 88 new light bulbs are tested. Would you buy the new version ofthe light bulb or would you buy the older version if the random sample showed an average of 750 hours? Use a 0.05 level ofsignificance."I will certainly buy the older version because I am 100% sure it is better.I will buy the older version until there is sufficient evidence to do otherwise.I will buy the new version.There is no sufficient data to make a sound conclusion.

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Answered: "An electrical firm produces light…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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It currently takes users a mean of 12 minutes to install the most popular computer program made by RodeTech, a software design company. After changes have been made to the program, the company executives want to know if the new mean is now different from 12 minutes so that they can change their advertising accordingly. A simple random sample of 91 new customers are asked to time how long it takes for them to install the software. The sample mean is 11.7 minutes with a standard deviation of 1.6 minutes. Perform a hypothesis test at the 0.05 level of significance to see if the mean installation time has changed. Step 2 of 3 : Compute the value of the test statistic. Round your answer to three decimal places.
Suppose that El Camino is studying the average number of hours students study for classes per week. According to research from 2010 El Camino students spent an average of 21 hours a week studying for classes. El Camino wants to study if this average has changed. To do this they take a random sample of 81 current students and find that the average student spent 19.3 hours studying with a standard deviation of 6.4 hours. (Note: You may assume there are approximately 20,000 El Camino students). (a) Carry out a hypothesis test at α = .05 to test the claim that the average number of hours per week that El Camino students study has changed since 2010. (b) Describe what it would mean in this situation to make a Type I error (c) Describe what it would mean in this situation to make a Type II error (d) Construct a 95% confidence interval for the average number of hours studied by El Camino students per week. Make sure to interpret your interval.
Fran is training for her first marathon, and she wants to know if there is a significant difference between the mean number of miles run each week by group runners and individual runners who are training for marathons. She interviews 42 randomly selected people who train in groups and finds that they run a mean of 47.1 miles per week. Assume that the population standard deviation for group runners is known to be 4.4 miles per week. She also interviews a random sample of 47 people who train on their own and finds that they run a mean of 48.5 miles per week. Assume that the population standard deviation for people who run by themselves is 1.8 miles per week. Test the claim at the 0.01 level of significance. Let group runners training for marathons be Population 1 and let individual runners training for marathons be Population 2. Step 2 of 3 : Compute the value of the test statistic. Round your answer to two decimal places.
You have obtained the number of years of education from one random sample of 38 police officers from City A and the number of years of education from a second random sample of 30 police officers from City B. The average years of education for the sample from City A is 15 years with a standard deviation of 2 years. The average years of education for the sample from City B is 14 years with a standard deviation of 2.5 years. Is there a statistically significant difference between the education levels of police officers in City A and City B?What is the appropriate test for this case? 2 sample z-testChi-square test 2-sample t-test2 sample paired t-test Carry out the test. The test statistic = (round answer to two decimal places.)and the p-value is (round answer to 2 decimal places)There sufficient evidence at the 5% level to conclude that the education levels of police officers in City A and City B is significantly different.
You are interested in studying the average gestational length of pregnancies among African American women in the United States to see if it is different from the rest of the US population. The population mean for gestational length is 39 weeks with a standard deviation of 2 weeks. You take a simple random sample of 22 African American women that gave birth in the last year and find that their mean gestational length is is 38.5 weeks. If you decide to conduct a two-sided test with α = .05. What is the power of this test?
The mean number of English courses taken in a two-year time period by male and female college students is believed to be about the same. An experiment is conducted and data are collected from 29 males and 16 females. The males took an average of three English courses with a standard deviation of 0.8. The females took an average of four English courses with a standard deviation of 1.0. Are the means statistically the same? (Assume a 5% level of significance.)
The breaking strengths of cables produced by a certain manufacturer have historically had a mean of 1800 pounds and a standard deviation of 90 pounds. The company believes that, due to an improvement in the manufacturing process, the mean breaking strength, μ, of the cables is now greater than 1800 pounds. To see if this is the case, 100 newly manufactured cables are randomly chosen and tested, and their mean breaking strength is found to be 1818 pounds. Can we support, at the 0.05 level of significance, the claim that the population mean breaking strength of the newly- manufactured cables is greater than 1800 pounds? Assume that the population standard deviation has not changed. Perform a one-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places, and round your responses as specified below. (If necessary, consult a list of formulas.) (a) State the null hypothesis Ho and the alternative hypothesis H₁. H :O 1 (b) Determine the…
The breaking strengths of cables produced by a certain manufacturer have historically had a mean of 1775 pounds and a standard deviation of 70 pounds. The Español company believes that, due to an improvement in the manufacturing process, the mean breaking strength, µ, of the cables is now greater than 1775 pounds. To see if this is the case, 16 newly manufactured cables are randomly chosen and tested, and their mean breaking strength is found to be 1806 pounds. Assume that the population is normally distributed. Can we support, at the 0.10 level of significance, the claim that the population mean breaking strength of the newly- manufactured cables is greater than 1775 pounds? Assume that the population standard deviation has not changed. Perform a one-tailed test. Then complete the parts below. 00 Carry your intermediate computations to three or more decimal places, and round your responses as specified below. (If necessary, consult a list of formulas.) (a) State the null hypothesis H,…
In a school district, all sixth grade students take the same standardized test. The superintendant of the school district takes a random sample of 3030 scores from all of the students who took the test. She sees that the mean score is 169169 with a standard deviation of 7.06747.0674. The superintendant wants to know if the standard deviation has changed this year. Previously, the population standard deviation was 1313. Is there evidence that the standard deviation of test scores has decreased at the α=0.005α=0.005 level? Assume the population is normally distributed. Step 1 of 5: State the null and alternative hypotheses. Round to four decimal places when necessary. Step 2 of 5: Determine the critical value(s) of the test statistic. If the test is two-tailed, separate the values with a comma. Round your answer to three decimal places. Step 3 of 5: Determine the value of the test statistic. Round your answer to three decimal places. Step 4 of 5: Make the…
Consumer agencies claim that the mean lifespan of a dishwasher is 9.5 years. Your company manufacturers dishwasher and you have been asked to see if this claim is true. You randomly survey 20 households who have recently purchased a dishwasher and ask them how long their previous dishwashers lasted and you calculate a mean of 8.9 years with a standard deviation of 3.1. Is the consumer agency’s claim that a dishwasher lasts 9.5 year correct? What is the p-value for this claim? Consumer agencies claim that the mean lifespan of a dishwasher is 9.5 years. Your company manufacturers dishwasher and you have been asked to see if this claim is true. You randomly survey 20 households who have recently purchased a dishwasher and ask them how long their previous dishwashers lasted and you calculate a mean of 8.9 years with a standard deviation of 3.1. Is the consumer agency’s claim that a dishwasher lasts 9.5 year correct? What is the p-value for this claim? 0.8012 0.1988 0.3975 -0.8656
pizza delivery chain advertises that it will deliver your pizza in 35 minutes from when the order is placed. Being a skeptic, you decide to test and see if the mean delivery time is actually more than 35 minutes. For the simple random sample of 7 customers who record the amount of time it takes for each of their pizzas to be delivered, the mean is 39.4 minutes with a standard deviation of 5.5 minutes. Assume that the population distribution is approximately normal. Perform a hypothesis test using a 0.025 level of significance. Step 3 of 3 : Draw a conclusion and interpret the decision.
The breaking strengths of cables produced by a certain manufacturer have historically had a mean of 1825 pounds and a standard deviation of 70 pounds. The company believes that, due to an improvement in the manufacturing process, the mean breaking strength, μ, of the cables is now greater than 1825 pounds. To see if this is the case, 17 newly manufactured cables are randomly chosen and tested, and their mean breaking strength is found to be 1844 pounds. Assume that the population is normally distributed. Can we support, at the 0.05 level of significance, the claim that the population mean breaking strength of the newly-manufactured cables is greater than 1825 pounds? Assume that the population standard deviation has not changed. Perform a one-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places, and round your responses as specified below. (If necessary, consult a list of formulas.) (a) State the null hypothesis H0…

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