Hypothesis Testing: With a 0.05 level of significance, can we conclude that the mean age of the workforce has declined?

A big multinational corporation based in Toronto recently moved it's production facilities to Mexico. When the corporation was in Toronto, it had an older, experienced labour force with a mean age of 45 years. Now that it has moved to Mexico, the company wishes to find out if the average age of the workforce has declined. A sample of 35 employees is selected. The average age is found to be 40 years, with a standard deviation of five years. With a 0.05 level of significance, can we conclude that the mean age of the workforce has declined?

Hypothesis Testing for proportions

The manufacturer of a nationally known "lite beer" claims that the approval rating for it's product is at least 85%. A local soft drink manufacturer has retained a marketing agency to test the "lite beer". A sample of 500 individuals participated in the test nationally. Out of the sample of 500, 100 indictated that they did not like the taste. Test the hypothesis the approval rating is at least 85% at the 0.10 level of significance.

A confidence interval of the mean is determined.

This problem is solved: Let's summarize the method for finding the 95% confidence interval using a step-by-step illustration. Suppose that a certain automobile company wishes to determine the expected miles per gallon for one of its new models. Based on years of experience with cars, the company statistician realizes that not all cars are equal, and that a standard deviation of 4 miles per gallon ( = 4) is to be expected due to variations in parts and workmanship. In order to estimate the mean miles per gallon for the new model, he test runs a random sample of 100 cars off the assembly line and obtains a sample mean of 26 miles per gallon. What steps are followed to obtaining a... click for more

Hypothesis testing is embedded.

The "Mars" division of a big auotmobile manufacturer specializes in manufacturing scooters for export. The company claims that these scooters average at least 55 miles per gallon in city driving. An independant consumer avocate road tested a sample of 25 scooters. The sample showed an average of 60 miles per gallon, with a standard deviation of 10 miles per gallon. At 0.10 level of significance, can the company's claim be rejected? This problem is worked.

Hypothesis Testing: Testing for proportions

Joe thinks that no more than 20% of students in his Statistics class will get an A in the final examination. To prove his claim, he takes a random sample of 35 students and finds to his surprise that 30% of students got an A. At a 0.01 percent level of significance can we reject Joe's claim?