Mathematical Methods · continuous random variables · manipulative

The bigger mark is not always better

Two tests, two bells. Subtract μ and divide by σ — both scores land on one z-line, and you can finally compare them.

Test A Test B z-line

Test A

Test B

Shared z-scale · standard normal

72 on a spread-out paper can beat 75 on a tight one — read the z-line, not the raw marks

Test A · teal

72
60
10

Test B · amber

75
70
5

Working