Suppose you have a random sample of 2,179 credit scores from a population of mortgage applicants with a sample mean of 620 and sample standard deviation of 70, and would like to calculate the t-stat for the null hypothesis that the population mean is 610. Which of the following is the correct construction of the t-stat?
A) $\frac { 620 - 610 } { 70 / \sqrt { 2179 } }$
B) $\frac { 620 - 610 } { 70 }$
C) $\frac { 620 } { 70 / \sqrt { 2179 } }$
D) $\frac { 610 - 620 } { 70 / \sqrt { 2179 } }$

Question

Quizplus · Accepted Answer

The correct formula for the t-stat for a one-sample t-test is (sample mean - hypothesized population mean) / (sample standard deviation / sqrt(sample size)).

Using this formula, we can see that the correct construction of the t-stat for this problem is (620 - 610) / (70 / sqrt(2179)) = 3.38. Therefore, the answer is choice letter A.

Suppose You Have a Random Sample of 2,179 Credit Scores 620−61070/2179\frac { 620 - 610 } { 70 / \sqrt { 2179 } }70/2179​620−610​

Suppose You Have a Random Sample of 2,179 Credit Scores $\frac { 620 - 610 } { 70 / \sqrt { 2179 } }$