Gregorio took two tests. Find his z-score for each test. (Remember: The number of standard deviations between a score and the mean score is indicated by a z-score.) On which did he score better compared with others in his class? Test A Test B Gregorio's score 62 70 Mean score 80 90 Standard deviation 6 10 a. Test A: 3; Test B: 2; Test A c. Test A: - 2; Test B: - 3; Test A b. Test A: - 3; Test B: - 2; Test B d. Test A: - 3; Test B: - 2; Test A

As the problem statement tells you,

... z = (x - μ) / σ

When you have multiple calculations of the same type, sometimes it is easier to do the calculation using a spreadsheet or a list. Here, we use a list for the numbers of [testA, testB], so we can put the calculations all in one expression. Math operations are performed on corresponding members of the list.

([62, 70] - [80, 90]) / [6, 10]

... = [-18/6, - 20/10] = [-3, - 2]

-2 > - 3, so Gregorio did better on Test B.

The appropriate answer choice is

... b. Test A: - 3; Test B: - 2; Test B