Question Details

Determine the critical value for this test 



1.	Automobiles manufactured by the Efficiency Company have been averaging 42 miles per gallon of gasoline in highway driving.  It is believed that its new automobiles average more than 42 miles per gallon.  An independent testing service road-tested 36 of the automobiles.  The sample showed an average of 42.8 miles per gallon with a standard deviation of 1.2 miles per gallon.

a.	With a 0.05 level of significance using the critical value approach, test to determine whether or not the new automobiles actually do average more than 42 miles per gallon.
b.	What is the p-value associated with the sample results?  What is your conclusion based on the p-value?


2.	The average starting salary of students who graduated from colleges of Business in 2009 was $48,400.  A sample of 100 graduates of 2010 showed an average starting salary of $50,000.  Assume the standard deviation of the population is known to be $8,000.  We want to determine whether or not there has been a significant increase in the starting salaries.

a.	State the null and alternative hypotheses to be tested.
b.	Compute the test statistic.
c.	The null hypothesis is to be tested at 95% confidence.  Determine the critical value for this test.
d.	What do you conclude?
e.	Compute the p-value.

3.	The average price of homes sold in the U.S. in the past year was $220,000.  A random sample of 81 homes sold this year showed an average price of $210,000.  It is known that the standard deviation of the population is $36,000.  At 95% confidence test to determine if there has been a significant decrease in the average price homes.

a.	State the null and alternative hypotheses to be tested.
b.	Compute the test statistic.
c.	Determine the critical value for this test .
d.	What do you conclude?
e.	Compute the p-value.




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