A car after travelling 18 km from a point A developed some problem in the engine and speed became 4/5 of its original speed. As a result, the car reached point B 45 minutes late. If the engine had developed the same problem after travelling 30 km from A, then it would have reached B only 36 minutes late. The original speed of the car (in km./hr) and the distance between the points A and B (in km) are
a) 25, 130
b) 30, 150
c) 20, 90
d) None of these
Ans: d) None of these
When the distance which is travelled at different speeds is 12 km, the difference in delay is (45 – 36) = 9 minutes.
if the actual difference in the time is 45 minutes, the distance will have to be 60 km.
the total distance is 30 + 60 = 90 km. we know that s1 : s2 :: 5 : 4, ∴ t1 : t2 :: 4 : 5.
The difference of 1 unit here corresponds to a difference of 9 minutes in reality, so the factor of multiplication is 9. The remaining part is now easy.
