What is the risk of performing the ttest using pooled varian

What is the risk of performing the t=test using pooled variance, if the variances between the 2 samples are actually unequal (i.e.. fail the F test) ?

Solution

The risk of performing the t-test using pooled variance, if the variances between the two samples are actually unequal is may falsely accept or reject the null hypothesis. Increase or decrease of Type I and Type error probabilities occurs when the variances of samples of different sizes are pooled to obtain an error term.