Places A and B are 144 km apart. Two cars start simultaneously, one from A and the other from B. If they move in the same direction, they meet after 12 hours, but if they move towards each other they meet after $\frac{9}{8}$ hours. The speed (in km/h) of the car moving at a faster speed, is:
Answer & explanation
Correct answer: option 1
We know ,
Speed = \(\frac{Distance}{Time}\)
Let speed of 1st car = a km/h & speed of 2nd car = b km/h
Relative speed when moves in same direction = (a - b) km/h
Relative speed when moves in opposite direction = (a + b) km/h
According to question ,
( a - b ) = \(\frac{144}{12}\) = 12 km/h
& ( a + b ) = \(\frac{144 × 8}{9}\) = 128 km/h
2a = 12 + 128 = 140
a = 70 km/h
So , speed of 1st car = 70 km/h