Here's the question you clicked on:
xEnOnn
Can I use a T-Statistic to construct a Confidence Interval for a sample collected from a large population? If no, why would it be wrong to use a T-Statistic in this case? If yes, also, what are the reasons for being correct to use?
What is T statistics
Student T-Statistic http://en.wikipedia.org/wiki/T-statistic