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  1. 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
    1. 15 km./hr.
    2. 18 km./hr.
    3. 10 km./hr.
    4. 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

x
+
y
= 15
22

⇒  x + y = 30   ..... (i)
Case II,
AD – BD = AB
⇒ x ×
5
− y ×
5
= 15
22

5
(x – y) = 15
2

⇒  x – y =
15 × 2
= 6   .....(ii)
5

∴  On adding equations (i) and (ii),
x + y + x – y = 30 + 6
⇒  2x = 36
⇒  x =
36
= 18 kmph.
2



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