A bag holds red and blue counters in the ratio 2 : 3. After 10 more red counters are added, the numbers of red and blue counters are equal. How many blue counters are there?
Answer and explanation
Correct answer: A. 30
- Step 1: Let red = 2k and blue = 3k.
- Step 2: Adding 10 red makes the numbers equal: 2k + 10 = 3k, so k = 10.
- Step 3: Blue = 3 x 10 = 30.
Answer
30.
Why not the others: 20 is the original number of red counters, 25 and 40 do not make the two colours equal after adding 10 red.
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