2 sample independent sample t test

[Jbueno]

View attachment 5824

Can someone please explain why you don't square the variance in this problem and do for others??

 

[Dason]

When do you ever square the variance? You sometimes square the standard deviation to get the variance. But what you're given is the variance already.

 

[blubblub]

When do you ever square the variance? .....

Actually in determining the degrees of freedom in a Welch t-test you square the variance.