Week6 Assignment 1

Question 1 – the concepts

Professor Nord stated that the mean score on the final exam from all the years he has been teaching is a 79%.  Colby was in his most recent class, and his class’s mean score on the final exam was 77%.  Colby decided to run a hypothesis test to determine if the mean score of his class was different than the mean score of the population.  α = .05.

         What is the mean score of the population?

         What is the mean score of the sample?

         Is this test one-tailed or two-tailed? Why?

         What are the null and alternative hypotheses in this case?

         Let’s pretend that p was calculated, and p = 0.09, should Colby reject or fail to reject the null hypothesis?  Why?

         What should Colby’s statement of conclusion be?  (This circles back to what is being tested).

The next two ask you do to a hypothesis test. Remember, hypothesis tests follow a series of steps. They are not just a computer printout.  Make sure if you use a computer printout, you identify which parts of the printout apply to the problem. All of the parts of the printout will NOT apply.

Question 2 – hypothesis test with guidance

A sample of 15 account balances of a credit company showed a mean customer balance of $4,300, but the marketing manager claimed that the mean balance for the population was $4425.  The marketing manager did NOT have the population standard deviation, but the sample standard deviation was found to be $400.  Use the p-value approach to conduct a full hypothesis test(all steps) that can be used to determine whether the mean of all account balances is significantly different from $4425.   Let α = .01.

To help you go through the steps of hypothesis testing, follow these prompts:

The null hypothesis is

The alternative hypothesis is

I will use a (choose 1: t sub alpha over two / z sub alpha over two) in my formula because 

I have calculated the value of t (or z) to be

I have used t (or z) to get the value of p (most likely from a chart or computer printout). My p value is

Alpha, which is given in the problem, is

When I compared p to alpha, p is (choose 1: greater than/less than) alpha.

Because of this, I know I should (choose 1: reject / fail to reject) my null hypothesis.

Choose one:  The mean balance is different than $4425 / The mean balance is NOT different than $4425.

Question 3 -on your own

A sample of 350 homes for sale in ABC City showed a mean asking price of $247,000, but the city claimed that the mean asking price for the population was $253,000.  The population standard deviation of all homes for sale was $8,000.  Use the p-value approach to conduct a full hypothesis test (all steps- follow the guidance in the last problem) that can be used to determine whether the mean asking price is significantly less than $253,000.   Let α = .10.