Question

NEED HELP

On a unit test in a statistics class, the teacher determines that the mean test grade was 77.5 with a standard deviation of 5.2. One student’s test grade was 91. What is the z-score for the student’s test?

–5.20
–2.60
2.60
5.20

Answer 1

2.60

Explanation:

z-score is the difference between the score and mean, divided by the standard deviation.

`z = (x - \mu)/(\sigma)`

`z = (91-77.5)/(5.2) = (13.5)/(5.2) \approx 2.596`

So 2.6 is an answer close enough.