It is the probability distribution used when the population variance is unknown and/or if the sample size is small.

When do we consider that the sample size is small?

In Student's t-distribution, what is the sample size of the degree of freedom is 25?

When do we use the t-distribution instead of normal distribution?

In the estimation of a parameter using the t-distribution, is it possible to replace the population standard deviation by a sample standard deviation?

It is a value in the t-distribution that is less than the probability of the given percentage.

If the area of the unshaded part of the t-distribution is 0.85, what is the area of the shaded region?

What is needed in order to identify a percentile using the t-table?

What is the 95th percentile of the t-distribution when the sample size is 23?

To what percentile of the disribution does 1.397 belongs if the sample size is 9?