Ateacher wants to see if a new unit on factoring is students learn. she has five randomly selected students take a pre-test and a post test on the material. the scores are out of 20. has there been improvement? (pre-post) what value of t would you use for the 90% confidence interval?

2.1318

Step-by-step explanation:

The critical value of t for ()% confidence interval is the  vt-value in students' t- distribution table corresponding to significance level and degree of freedom n-1 (n= sample size) .

A per given , we have

sample size : n= 5

Degree of freedom : df = n-1 = 4

Confidence level :

Significance level :

Then , By students' t- distribution table:

Critical t- value for 90% confidence interval will be :

Hence, the t-value we use for the 90% confidence interval = 2.1318

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