When is it appropriate to use the t test?

[sara_87]

Homework Statement

If i have data and want to compare the two means, when is it appropriate to use the t test?

The Attempt at a Solution

i know its because the distribution is normal but there are also other reasons.
Thank you.

 

[happyg1]

the t-test is used when the sample size is "small" less than 30 and the underlying distribution is normal.