Distance between A and B is 420 km. When they start moving towards each other they meet in 7 hours. If A start moving 4 hours after B then they meet in 6 hours. Find speed of A (in km/hr).
Answer & explanation
Correct answer: option 4
420 km
A -------------------B
Let the speed of A is S1 km/h & that of B is S2 km/h.
ATQ,
\(\frac{420}{S_1 + S_2}\) = 7
⇒ S1 + S2 = 60 ------- (i)
A start moving 4 hours after B, Hence
4S2 + (S1 + S2) × 6 = 420
Put the value of (S1 + S2) from eqn (i)
4S2 + 60 × 6 = 420
4S2 = 420 - 360
4S2 = 60
S2 = 15 km/h
We have S1 + S2 = 60 km/h
S1 + 15 = 60
S1 = 45 km/h