stats homework help

[rusty JEDI]

I missed something in class.

Question: given alpha = 0.05, the critical t with 14 degrees of freedom woudl be 2.145. Is Samuel's score significantly different from those of his classmates.

X = 97
-
X = 75
sd = 12.93
N = 27
Z = 1.7
t = 8.83

[danzasmack]

what is what? why do you need t if you have the standard deviation?

[elitegimp]

I might be missing something, but since t (8.83) > crit t (2.145), wouldn't the answer just be "yes"? You did all the work already...

[danzasmack]

srry - meant to just edit other post

if you have to do a significance test i dont see how what you're "given" has to do with anything. Your data on the bottom has 26 degrees of freedom. But that too seems irrelevant unless the class has more than 27 students.

If the class has exactl 27 student and 75 is the population mean, sd = 12.93 you can just do a z test. you do not need t at all.

Since there are no specifications we have to assume this is 2 tailed (since it is just "different" not "greater than"). In a normal distribution 2sd contains ~95% of all points, so no, his score is not significantly different if the z = 1.7

Edit: you can check this out using the Z-chart to see where 1.7 is at.

[rusty JEDI]

Okay.

Today in class we went over the question and there were problems with the way the teacher wrote it. It was supposed to be 26 degrees of freedom and 2.779 with a 1 tailed test. She gave us the wrong question parameters.

Thanks

rJ