Before changes to its management staff, an automobile assembly line operation had a scheduled mean completion time of 14.2 minutes. The standard deviation of completion times was 1.3 minutes. An analyst at the company suspects that, under new management, the mean completion time, μ, is now less than 14.2 minutes. To test this claim, a random sample of 100 completion times under new management was taken by the analyst. The sample had a mean of 13.9 minutes. Can we support, at the 0.10 level of significance, the claim that the population mean completion time under new management is less than 14.2 minutes? Assume that the population standard deviation of completion times has not changed under new management. 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. HO H₁ : (b) Determine the type of test statistic to use. (Choose one) (c) Find the value of the test statistic. (Round to three or more decimal places.) (d) Find the p-value. (Round to three or more decimal places.) (e) Can we support the claim that the population mean completion time under new management is less than 14.2 minutes? O Yes O No 3. H Ix ロロ a X S 0=0 OSO Do OO

to qualify for membership in a certain high-IQ society a person must score in the upper 2% of the population on an IQ test. the minimum IQ score to be in the upper 2% is a 140.5 if Iq scores are normanlly distributed with a standrd deviation of 10, what is the mean IQ score?

Use the following information to answer the next four questions. A manager of a fast-food chain wants to analyze the length of time a vehicle spends at the drive-through window waiting for an order. According to records obtained from the chain, the population mean time spent waiting at the window was 236.5 seconds with a population standard deviation of 34.8 seconds. It is known that the distribution of time waiting at the window is extremely right-skewed. The waiting time was recorded for a random sample of 21 vehicles. For the random sample obtained, the sample mean waiting time was found to be 254.6 seconds with a sample standard deviation of 23.1 seconds. In this example, for the numerical values 236.5 and 254.6 O a. 236.5 is a parameter, 254.6 is a statistic O b. Both are parameters O C. Both are statistics O d. 236.5 is a statistic, 254.6 is a parameter

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 22 respondents who were college graduates employed full time. The mean number of hours worked per week by these 22 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. Can we conclude that mean is greater than 40 hours? Use the 0.1 level of significance. Perform a one tailed test, and complete the parts below.

In Professor Krugman’s economics course, the correlation between the students’ total scores prior to the final examination and their final‑examination scores is ?=0.5.r=0.5. The pre‑exam totals for all students in the course have mean 280280 and standard deviation 40.40. The final‑exam scores have mean 7575 and standard deviation 8.8. Professor Krugman has lost Julie’s final exam but knows that her total before the exam was 300.300. He decides to predict her final‑exam score from her pre‑exam total. (a) Which of the choices is the least‑squares regression line of final‑exam scores on pre‑exam total scores in this course?

In Professor Krugman's economics course, the correlation between the students' total scores prior to the final examination and their final‑examination scores is ?=0.5.�=0.5. The pre‑exam totals for all students in the course have mean 280280 and standard deviation 40.40. The final‑exam scores have mean 7575 and standard deviation 8.8. Professor Krugman has lost Julie's final exam but knows that her total before the exam was 300.300. He decides to predict her final‑exam score from her pre‑exam total.   © Macmillan Learning (a) What is the slope of the least-squares regression line of final-exam scores on pre-exam total scores in this course? Give your answer to one decimal place. slope:     What is the intercept? Give your answer as a whole number. intercept:

The president of a college wants to determine the mean number of units that college students take per semester. How large of a sample is required in order to be 99% sure that a sample mean will be off by no more than 1.25 units? An initial study suggested that the standard deviation is approximately 2.1 units.

Suppose that you are designing an instrument panel for a large industrial machine. The machine requires the person using it to reach 2 feet from a particular position. The reach from this position for adult women is known to have a mean of 2.7 feet with a standard deviation of 0.5. The reach for adult men is known to have a mean of 3.1 feet with a standard deviation of 0.7. Both women's and men's reach from this position is normally distributed. If this design is implemented, (a) what percentage of women will not be able to work on this instrument panel? (b) What percentage of men will not be able to work on this instrument panel? (c) Explain your answers to a person who has never had a course in statistics. Click here to view page 1 of the table. Click here to view page 2 of the table. Click here to view page 3 of the table. Click here to view page 4 of the table.

Steve believes that his wife's cell phone battery does not last as long as his cell phone battery. On eight different occasions, he measured the length of time his cell phone battery lasted and calculated that the mean was 19.7 hours with a standard deviation of 9.4 hours. He measured the length of time his wife's cell phone battery lasted on twelve different occasions and calculated a mean of 18.9 hours with a standard deviation of 5.3 hours. Assume that the population variances are the same. Let Population 1 be the battery life of Steve's cell phone and Population 2 be the battery life of his wife's cell phone. Step 1 of 2: Construct a 90 % confidence interval for the true difference in mean battery life between Steve's cell phone and his wife's. Round the endpoints of the interval to one decimal place, if necessary.