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1- What is the critical t -value for a two-tailed test with alpha .05 and 18 deg

ID: 3074505 • Letter: 1

Question

1- What is the critical t-value for a two-tailed test with alpha .05 and 18 degrees of freedom? Write your answer with THREE decimals points !

2- Which of the following examples is not a test with dependent samples.

a- Comparing mean life satisfaction scores for seniors (age 65+) and for middle-aged adults (ages 40-50).

b- Comparing pre- and post-test number of hours of sleep daily.

c- Comparing number of alcoholic drinks consumed in a typical day for pairs of twins.

d- Comparing the number of words read per minute for students before and after a class in speed reading

3- Select the correct formula for the degrees of freedom for a t-test of the differences between two means with independent samples and approximately equal variances.

A- n-1

B- k-1

c- (r-1)(c-1)

D- (n1+n2)-2

Explanation / Answer

1- What is the critical t-value for a two-tailed test with alpha .05 and 18 degrees of freedom?

Answer: The critical value of t for 18 at 5% significance level and for two tailed test is +/-2.101

Q2) Which of the following examples is not a test with dependent samples.

Answer: a- Comparing mean life satisfaction scores for seniors (age 65+) and for middle-aged adults (ages 40-50).

because the group of seniors and middle aged adults are independent to each other.

Q3 )  Select the correct formula for the degrees of freedom for a t-test of the differences between two means with independent samples and approximately equal variances.

Answer: D- (n1+n2)-2