Eight years ago, the ratio of the ages of A and B was 4:5 and the ratio of their ages, 12 years hence. will be 13 : 15. The present
age (in years) of B is:
This questions was previously asked in
SSC MTS 14th October 2021 Shift-2
Explanation:
Let's solve step by step:
- Let present ages be A and B.
- 8 years ago: A was (A-8), B was (B-8).
- (A-8)/(B-8) = 4/5 ? 5(A-8) = 4(B-8)
- 12 years hence: (A+12)/(B+12) = 13/15 ? 15(A+12) = 13(B+12)
Let's solve:
Equation 1: 5A-40 = 4B-32 ? 5A-4B = 8
Equation 2: 15A+180 = 13B+156 ? 15A-13B = -24
Let’s solve these:
From Eq 1: 5A - 4B = 8
Multiply Eq 1 by 3 to align coefficients:
15A - 12B = 24
Now subtract Eq 2:
(15A-12B) - (15A-13B) = 24-(-24)
15A-12B-15A+13B = 24+24
B = 48
Options:
- Option 1: 52
- Option 2: 46
- Option 3: 48
- Option 4: 56
Conclusion:
- The present age of B is 48 years.
- Option 3 is correct.
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