Posted by Dorothy on Friday, December 30, 2011 at 11:58pm.
A college professor believes that students take an average of 15 credit hours per semester. A random sample of 24 students in his class of 250 reported the following number of credit hours that they were taking: 12,13,14,14,15,15,15,16,16,16,16,16,17,17,17,18,18,18,18,19,19,19,20,21
Does this sample indicate that students are taking more credit hours than the professor believes? BEFORE jumping to an answer, work through this problem using the following steps:
1) What are your null and alternative hypotheses? Answer verbally and with mathematical symbols.
2) One condition to check is that the data should be ¡§Nearly normal¡¨, or roughly unimodal and symmetric. Create a histogram or boxplot of the data and assess this condition.
3) Is the sampling distribution of the mean a z or a student¡¦s t statistic? Why?
4) Specify the decision rule using ƒÑƒnƒƒn.05.
5) Sketch a normal curve graphic identifying the critical value and rejection area labeling the mean and the values. It is OK to draw this by hand and scan it into your document.
6) Calculate the test statistic using MegaStat.
7) Make the decision and state your conclusion in the context of this problem.
8) Regardless of its statistical significance, comment on the practical importance of the difference in credit load.
9) If this sample of students was extremely unusual and your conclusion was wrong (based on the entire population of students taking this professor¡¦s classes), what type error would you be committing? Why?
10) Find a 95% confidence interval for the number of credit hours taken by the students in the professor¡¦s class. Summarize what this interval means in one or two sentences.

statistics  PsyDAG, Saturday, December 31, 2011 at 1:13am
We do not do your work for you. Once you have attempted to answer your questions, we will be happy to give you feedback on your work. Although it might require more time and effort, you will learn more if you do your own work. Isn't that why you go to school?

statistics  Dorothy, Saturday, December 31, 2011 at 8:31pm
Isn't that why you go to school? Is this sarcasm or what maybe scorn? Really!!!