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Two numbers are in the ratio 3 : 5. If each number is increased by 10, the ratio becomes 5 :7. The smaller number is
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- 9
- 12
- 15
- 25
Correct Option: C
Let the numbers be 3x and 5x.
| ∴ | = | ||
| 5x + 10 | 7 |
⇒ 25x + 50 = 21x + 70
⇒ 4x = 20
⇒ x = 5
∴ Smaller number = 3x
= 3 × 5 = 15
Second Method :
Here, a = 3, b = 5, c = 5, d = 7, x = 10
∴ Smaller number
| = | ∵ a < b | |
| ad − bc |
| = | |
| 3 × 7 − 5 × 5 |
| = | |
| 21 − 25 |
| = | = 15 | |
| 4 |
