Question

Tevin and Taylor began arguing about who did better on their tests, but they couldn't decide who did better given that they took different tests. Tevin took a test in Science and earned a 78.6, and Taylor took a test in Math and earned a 67.6. Use the fact that all the students' test grades in the Science class had a mean of 72.4 and a standard deviation of 11.8, and all the students' test grades in Math had a mean of 65.5 and a standard deviation of 9.3 to answer the following questions.

a) Calculate the z-score for Tevin's test grade.
z=z=


b) Calculate the z-score for Taylor's test grade.
z=z=


c) Which person did relatively better?

• Tevin
• Taylor
• They did equally well.

Answer 1

a) For Science class,

Mean = 72.4 and standard deviation = 11.8

score obtained in Science = 78.6

The z-score for Tevin's test grade

b) For Math class,

Mean = 65.5 and standard deviation = 9.3

score obtained in Math = 67.6

The z-score for Taylor's test grade

c) Since z-score for Tevin's test grade > z-score for Taylor's test grade, so we can say that Tevin did relatively better.