Question : A and B are 15 km 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 a speed of:
Option 1: 15 km/h
Option 2: 18 km/h
Option 3: 10 km/h
Option 4: 8 km/h
Correct Answer: 18 km/h
Solution :
Let the speeds of A and B be
When moving on opposite sides, relative speed = (a + b) km/h.
When moving on the same sides, relative speed = (a – b) km/h.
According to the question, (Using: Relative speed =
⇒
Also
⇒
By solving equation 1 and equation 2 we get,
So, the faster of the two travels at a speed of 18 km/h.
Hence, the correct answer is 18 km/h.
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