Multiple choice

A train meets with an accident after travelling 30 km, after which it moves with4/5th of its original speed and arrives at the destination 45 minutes late. Had the accident happened 18 km further on, it would have been reached the destination 9 minutes before the time in the first case. Find the original speed of the train.

  1. 25 kmph

  2. 15 kmph

  3. 30 kmph

  4. 7.5 kmph
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let original speed be v. After 30km, distance D remains. Time taken = D/v. New time = D/(0.8v). Difference = 0.25(D/v) = 45 min = 0.75 hr. D/v = 3 hr. If accident was 18km later, distance D-18 remains. Time saved = 9 min = 0.15 hr. 0.25(D/v) - 0.25((D-18)/v) = 0.15. 0.25(18/v) = 0.15. 4.5/v = 0.15. v = 30 kmph.

Keep practicing — related questions