Question

Complete parts ​(a) through ​(c) below.

​(a) Determine the critical​ value(s) for a​ right-tailed test of a population mean at the alphaα=.10 with 15 degrees of freedom. tcrit=

b) Determine the critical​ value(s) for a​ left-tailed test of a population mean at the α=0.05 level of significance based on a sample size of n=20

c) Determine the critical​ value(s) for a​ two-tailed test of a population mean at the α=.01 level of significance based on a sample size of n=18

Answer 1

a) Using Excel, t-critical value at α=.10 with 15 degrees of freedom for right-tailed test,

Excel Command : TINV(0.20, 15) = 1.341

=> t_{​​​​​​crit} = 1.341

b) n = 20, degrees of freedom = 20 - 1 = 19

Using Excel, t-critical value at α= 0.05 with 19 degrees of freedom for left-tailed test,

Excel Command : TINV(0.10, 19) = 1.719

Since, it is left-tailed test,

=> t_{​​​​​​crit} = -1.729

c) n = 18, degrees of freedom = 18 - 1 = 17

Using Excel, t-critical value at α= 0.01 with 17 degrees of freedom for Two-tailed test,

Excel Command : TINV(0.01, 17) = 2.898

Since, it is Two-tailed test,

=> t_{​​​​​​crit} = 2.898

Critical values are: -2.898, 2.898