Question

A class of 28 students has 7 juniors and 21 seniors. The average (arithmetic mean) score of the juniors on a test was 73. The average score of the seniors on the test was y. The average score of the entire class on the test was 85. Find y.

Answer 1

89

Explanation:

Given that the class has 28 students has 7 juniors and 21 seniors

mean score of the juniors = 73

Therefore, total score of junior = 73 × 7

= 511

mean score of seniors = y

Total score of seniors = 21y

Total score of the class = 511 + 21y

Mean score of the class = 85

Total score of the class = 85 × 28

= 2380

therefore,

511 + 21y = 2380

21y = 2380 -511

21y = 1869

y = 1869/21

y = 89