Posted by Terra on Tuesday, November 17, 2009 at 11:48pm.
Suppose that the average grade for all people who take this course in statistics is 83 with a standard deviation of 3.5. If your particular class has an average of 89, can you conclude that your class is better than average at the 90 percent confidence level? Sample size 21.
Identify one or twotailed
States the Null and Alternative Hypothesis
States the Level of Significance
Calculates Test Statistic
Formulates Decision Rule
Makes a Conclusion

Statistics  MathGuru, Thursday, November 19, 2009 at 12:10pm
Null hypothesis:
Ho: µ = 83 >meaning: population mean is equal to 83
Ha: µ does not equal 83 >meaning: population does not equal 83
Since the problem is using confidence intervals, remember that 5% (or .05) will be below the interval and 5% (or .05) will be above the interval. This will be a twotailed test.
Using the ztest formula to find the test statistic:
z = (sample mean  population mean)/(standard deviation divided by the square root of the sample size)
z = (89  83)/(3.5/√21)
Finish the calculation.
Determine whether or not to reject the null. If you reject the null, you will conclude a difference.
I hope this will help get you started.