Civil Service Exam Reviewer · Ratio and Proportion · hard
A box has red and blue balls in the ratio 5 : 6. After 12 red balls are removed, the ratio becomes 1 : 2. How many blue balls are in the box?
- 30
- 36
- 66
- 48
Answer
B. 36
Solution
Red = 5k, blue = 6k. (5k − 12)/6k = 1/2 → k = 6. Blue = 6 × 6 = 36.
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