CEMC Cayley, 2006

Algebra Difficulty 1.0 Junior Find the answer Canada

A class of $30$ students recently wrote a test. If $20$ students scored $80$ , $8$ students scored $90$ , and $2$ students scored $100$ , then the class average on this test was

(A) $90$ (B) $84$ (C) $82$ (D) $86$ (E) $88$

We don't reproduce this publisher's solutions. Their own solution is here — work the problem first.

Want a route through all this instead of an archive? The track puts 2,604 problems in a working order, from Junior Challenge level to the IMO shortlist.

Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project. Solutions are the publisher's, linked not copied.