The human resources department of a consulting firm gives a standard creativity test to a randomly selected group of new hires every year. This year, 100 newhires took the test and scored a mean of 113.6 points with a standard deviation of 134. Last year, 95 new hires took the test and scored a mean of 116.4 pointswith a standard deviation of 16.8. Assume that the population standard deviations of the test scores of all new hires in the current year and the test socores of allnew hires last year can be estimated by the sample standard deviations, as the samples used were quite large. Construct a 90 confidence interval forthe difference between the mean test score , of new hires from the current year and the mean test score , of new hires from last year. Then tind the lowerlimit and upper limit of the 905% confidence interval.Carry your intermediate computations to at least three decimal places. Round your answeis to at least two decimal places. (If necessary, cosult a list.otfocmulas.)Lower limit: |Upper limit: 0

Givensample size(n1)=100Mean(x1)=113.6standard deviation(σ1)=13.4sample…

Answered: The human resources department of a…

A First Course in Probability (10th Edition)

10th Edition

ISBN:9780134753119

Author:Sheldon Ross

Publisher:Sheldon Ross

Chapter1: Combinatorial Analysis

Section: Chapter Questions

Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...

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Assume that an intelligence test scores are distributed normallt with a mean of 100 and a standard deviation of 15. If you scored 124 on this intelligence test, what is your z-score on this distribution.
A professor believes that, for the introductory art history classes at his university, the mean test score of students in the evening classes is lower than the mean test score of students in the morning classes. He collects data from a random sample of 150 students in evening classes and finds that they have a mean test score of 88.8. He knows the population standard deviation for the evening classes to be 8.4 points. A random sample of 250 students from morning classes results in a mean test score of 89.9. He knows the population standard deviation for the morning classes to be 5.4 points. Test his claim with a 99% level of confidence. Let students in the evening classes be Population 1 and let students in the morning classes be Population 2. Step 3 of 3 : Draw a conclusion and interpret the decision.
It seems these days that college graduates who are employed full-time work more than 40-hour weeks. Data are available that can help us decide if this is true. A survey was recently sent to a group of adults selected at random. There were 15 respondents who were college graduates employed full-time. The mean number of hours worked per week by these 15 respondents was 43 hours, with a standard deviation of 8 hours. Assume that the population of hours worked per week by college graduates employed full-time is normally distributed with mean μ. Can we conclude that μ is greater than 40 hours? Use the 0.05 level of significance. State the null hypothesis H0 and the alternative hypothesis H1 Find the t-test df & Solve the t-test value Find the critical value Can we conclude, at the 0.05 level of significance, that the mean number of hours worked per week by college graduates is greater than 40 hours? Yes or No?
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 40, respectively. If we conduct a hypothesis test, the p-value is Group of answer choices 0.0000 0.0010 0.0004 0.0002
A professor believes that, for the introductory art history classes at his university, the mean test score of students in the evening classes is lower than the mean test score of students in the morning classes. He collects data from a random sample of 250 students in evening classes and finds that they have a mean test score of 76.8. He knows the population standard deviation for the evening classes to be 7.2 points. A random sample of 200 students from morning classes results in a mean test score of 77.8. He knows the population standard deviation for the morning classes to be 1.9 points. Test his claim with a 90% level of confidence. Let students in the evening classes be Population 1 and let students in the morning classes be Population 2. Step 2 of 3 : Compute the value of the test statistic. Round your answer to two decimal places.
You are a teacher at a gifted school, and you feel that the newest class of students is even brighter than usual. The mean IQ at your school is 127, and the mean IQ of this new class is 134. In total, there are 32 students in this new class. Also, the standard deviation of the school’s IQ is 8. Use the eight steps to test whether this new class of students is significantly more intelligent than the school’s student body overall.
Suppose a paper reported that the freshman year weight gain for the students in a representative sample of 103 freshmen at a midwestern university was 5.6 pounds and that the standard deviation of the weight gain was 6.9 pounds. The authors also reported that 75.7% of these students gained more than 1.3 pounds, 17.4% maintained their weight within 1.3 pounds, and 6.8% lost more than 1.3 pounds. ***Calculate a 95% confidence interval (in pounds) for the population mean weight gain of freshmen students at this university. (Round your answers to three decimal places.)
Two popular brands of tires for tractor-trailers are the Puma and the Eternal. Salma is a buyer for a major shipping company and wants to determine if there is any difference between the two brands of tire in the mean distance (in thousands of km) driven on them before they need to be replaced. In the company's testing lab, Salma tests a random sample of 14 Puma tires and a random sample of 15 Eternal tires. (These samples are chosen independently.) For the Puma tires, the sample mean distance (in thousands of km) until they would need to be replaced is 54.71 with a sample variance of 5.95. For the Eternal tires, the sample mean distance (in km) until they would need to be replaced is 50.21 with a sample variance of 37.75. Assume that the two populations of distances driven are approximately normally distributed. Can Salma conclude, at the 0.05 level of significance, that there is a difference between the population mean of the distances (in thousands of km) driven on Puma tires before…
Brianna and Miranda began arguing about who did better on their tests, but they couldn't decide who did better given that they took different tests. Brianna took a test in Art History and earned a 78.3, and Miranda took a test in Social Studies and earned a 61.2. Use the fact that all the students' test grades in the Art History class had a mean of 71.3 and a standard deviation of 11.7, and all the students' test grades in Social Studies had a mean of 62.3 and a standard deviation of 8.2 to answer the following questions. a) Calculate the z-score for Brianna's test grade. [Round your answer to two decimal places.] = 2 b) Calculate the z-score for Miranda's test grade. [Round your answer to two decimal places.] c) Which person did relatively better? Brianna O Miranda They did equally well. Submit Question logi $22 3 FI F5 F7 % & W R T. Y. こ9 * CO
A professor believes that, for the introductory art history classes at his university, the mean test score of students in the evening classes is lower than the mean test score of students in the morning classes. He collects data from a random sample of 250 students in evening classes and finds that they have a mean test score of 76.8. He knows the population standard deviation for the evening classes to be 7.2 points. A random sample of 200 students from morning classes results in a mean test score of 77.8. He knows the population standard deviation for the morning classes to be 1.9 points. Test his claim with a 90% level of confidence. Let students in the evening classes be Population 1 and let students in the morning classes be Population 2. Step 1 of 3 : State the null and alternative hypotheses for the test. Fill in the blank below. H0: μ1=μ2 Ha: μ1__μ2
According to the historical data, the life expectancy in Belgium is less than the life expectancy in the United States. A new study has been made to see whether this has changed. Records of 260 individuals from Belgium who died recently are selected at random. The 260 individuals lived a mean of 78.4 years with a standard deviation of 8.8 years. Records of 285 individuals from the United States who died recently are selected at random and independently. The 285 Individuals lived a mean of 76.5 years with a standard deviation of 7.4 years. Assume that the population standard deviations of lifetimes in these two countries can be estimated by the sample standard deviations, as the samples used were quite large. Construct a 95% confidence interval for ₁-₂, the difference between the life expectancy μ₁ in Belgium and the life expectancy μ₂ in the United States. Then find the lower limit and upper limit of the 95% confidence interval. Carry your intermediate computations to at least three…
In a school district, all sixth grade students take the same standardized test. The superintendant of the school district takes a random sample of 30 scores from all of the students who took the test. She sees that the mean score is 169 with a standard deviation of 7.0674. The superintendant wants to know if the standard deviation has changed this year. Previously, the population standard deviation was 13. Is there evidence that the standard deviation of test scores has decreased at the α=0.005 level? Assume the population is normally distributed. Step 4: Make a decision. Is it reject Null hypothesis or Fail to reject Null hypothesis? Step 5: What is the conclusion? Is there sufficient evidence or there is not sufficient evidence to show that the standard deviation of the test scores has decreased?

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