Question

Use the calculator provided to solve the following problems.

Consider a t distribution with 20 degrees of freedom. Compute P(t ?1.39). Round your answer to at least three decimal places.

Consider a t distribution with 25 degrees of freedom. Find the value of c such that P (?c < t < c) =0.90. Round your answer to at least three decimal places.

Answer 1

The t-critical value for a right-tailed test, for a significance level of ?=0.09 is

tc?=1.389

Graphically

Hence P(t ?1.39)=0.09

The t-critical values for a two-tailed test, for a significance level of ?=0.9 are

tc?=?0.127 and tc?=0.127

Graphically

Hence value of c is 0.127