Download 6 Questions on Hypothesis Testing in Business Statistics I - Exam | STAT 226 and more Exams Statistics in PDF only on Docsity! stat 226 Hypothesis Testing Handout 9 1. State the appropriate null and alternative hypothesis in each case (a) Larry’s car averages 32 miles per gallon on the highway. He now switches to a new motor oil that is advertised as increasing gas mileage. After driving 3000 highway miles with the new oil, he wants to determine if his gas mileage actually has increased. (b) The diameter of a spindle in a small motor is supposed to be 5 mm. if the spindle is either too small or too large, the motor will not perform properly. The manufacturer measures the diameter in a sample of motors to determine whether the mean diameter has moved away from the target. (c) An economist believes that among employed young adults there is a positive correlation between income and the percent of disposable income that is saved. To test this, she gathers income and savings data from a sample of employed persons in her city aged 25 to 34. (d) A sociologist asks a large sample of high school students which academic subject they lie best. She suspects that a higher percent of males than of females will name economics as their favorite subject. 2. In a test H0 : µ = 100 vs. Ha : µ > 100, the sample data yielded a test statistics z = 2.17. What is the p-value for the test? What is an interpretation of the p-value? 3. A survey of CPAs across the United States found that the average net income for sole proprietor CPAs is $74,914. Because this survey is now more than 10 years old, an accounting researcher wants to test this figure by taking a random sample of 112 sole proprietor accountants across the United States to determine whether the net income figure has changed. The sample yielded a mean income of $79,268. Assume the population standard deviation of net incomes for sole proprietor CPAs is $14,530. (a) Test the researchers claim at the α = 0.05 level of significance.
