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A and B are 15 kms apart and when travelling towards each other meet after half an hour whereas they meet two and a half hours later if they travel in the same direction. The faster of the two travels at the speed of
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- 15 km./hr.
- 18 km./hr.
- 10 km./hr.
- 8 km./hr.
Correct Option: B
A’s speed = x kmph.
B’s speed = y kmph.
When A and B move in opposite
directions they meet at C and
when they move in the same direction, they meet at D.
Case I,
AC + CB = AB
| + | = 15 | ||
| 2 | 2 |
⇒ x + y = 30 ..... (i)
Case II,
AD – BD = AB
| ⇒ x × | − y × | = 15 | ||
| 2 | 2 |
| (x – y) = 15 | |
| 2 |
| ⇒ x – y = | = 6 .....(ii) | |
| 5 |
∴ On adding equations (i) and (ii),
x + y + x – y = 30 + 6
⇒ 2x = 36
| ⇒ x = | = 18 kmph. | |
| 2 |
