Multiple choice

The average age of A and B is 20 years. If C were to replace A, the average would be 19 and if C were to replace B, the average would be 21, what are the ratio of ages of A, B and C? A और B की औसत आयु 20 वर्ष है। यदि C, A के स्थान पर आये तो औसत 19 होगा और यदि C, B के स्थान पर आये तो औसत 21होगा। A, B और C की आयु का अनुपात क्या है?

  1. 6 : 5 : 7

  2. 9 : 7 : 3

  3. 13 : 7 : 11

  4. 11 : 9 : 10
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D Correct answer
Explanation

Using the average information, we get three equations: A+B=40, B+C=38, A+C=42. Solving this system gives A=22, B=18, C=20. The ratio 22:18:20 simplifies to 11:9:10 when divided by 2. This problem requires setting up and solving a system of linear equations from average information.

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