Question

Last week Andi had exams in Chemistry and in Spanish. On the chemistry exam, the mean was µ = 30 with σ = 5, and Andi had a score of X = 45. On the Spanish exam, the mean was µ = 60 with σ = 6 and Andi had a score of X = 65. For which class should Andi expect the better grade?

Answer 1

Chemistry

Explanation:

To solve the above question, we use the z score formula

Andy took two Exams, Chemistry and Spanish. So we find the z score for both exams.

a) Chemistry Exam

On the chemistry exam, the mean was µ = 30 with σ = 5, and Andi had a score of X = 45

z-score is given as: z = (x-μ)/σ

where x is the raw score,

μ is the population mean

σ is the population standard deviation

z = (x-μ)/σ

z = (45 - 30)/5

z = 15/5

z = 3

b) On the Spanish exam, the mean was µ = 60 with σ = 6 and Andi had a score of X = 65.

z-score is given as: z = (x-μ)/σ

where x is the raw score,

μ is the population mean

σ is the population standard deviation

z = (x-μ)/σ

z = (65 - 60)/6

z = 5/6

z = 0.8333333333

Comparing the z score of both Exams,

Andy had a z score of 3 in the Chemistry exam and 0.8333333333 in the Spanish exam.

Therefore, Andy should be expecting a better grade in the Chemistry exam because his z score in the Chemistry exam was higher than that of the Spanish exam.