Question

Complete the following statement regarding the relationship between the Z and t distributions.

Z is a special case of t as the number of degrees of freedom approaches ___________.

Answer 1

Z is a special case of t as the number of degrees of freedom approaches

• We use t-distribution instead of Z-distribution because we don't know true population standard deviation, so we must use sample standard deviation when estimating the Standard error.
• At degrees of freedom, the t-distribution and Z-distribution looks like same, and when then the t-distribution and Z-distribution looks exactly the same, i.e., there is no difference between Z and t distribution.