Multiple choice

In a classroom, there are x students whose average score on a test is 80. If y more students, whose average score is 90, join the classroom, then the average score of all the students in the classroom becomes 85. What is the ratio of y to x?

  1. 1 : 1

  2. 1 : 2

  3. 2 : 1

  4. 2 : 3

  5. a
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A Correct answer
AI explanation

The total score of x students is 80x and the total score of y students is 90y. The new combined average is (80x + 90y) divided by (x + y) equals 85. Solving this equation, 80x + 90y = 85x + 85y, which simplifies to 5y = 5x. Therefore, the ratio of y to x is 1 : 1.

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