hint:
If and are independent normal random variables, then:
Random sample of math scores assumed to be : X1=644, X2=493, X3=532, X4=462, X5=565
Random sample of verbal scores assumed to be : Y1=623, Y2=472, Y3=492, Y4=661, Y5=540, Y6=502, Y7=549, Y8=518
How do I find a 90% confidence level for ?
This one is finally well worded.
You want to pool the sample variances because we are assuming that the two population variances are equal.
It will be a t with degrees of freedom.
see.. Unequal sample sizes, equal variance (Ignore uequal sample size comment)
at http://en.wikipedia.org/wiki/Student's_t-test
Thank you for all the help on this problem. I do not understand why the population variances are equal, or how you figure that. I have been going through different books and thought I could just use the equation that uses just the sample means and variances with the t value from the table. I'm sure I'm wrong, I just can't figure out how to tell that the pop variances are equal. Thanks