Question

soman drives his car at constant speed. if he travels at 10km and 800m in 12 minute .what is the speed per hour at which he travels?

Answer 1

Let the distance to his office be D km

∴ the time taken at 10 kmph would be D/10 and the time taken at 15 kmph would be D/15

As per the question the time difference between the two = 2 hrs (1 p.m. – 11 a.m.)

⇒ D/10 – D/15 = 2 hrs

D = 60 km

∴ he takes 60/10 = 6 hrs when he travels at 10 kmph i.e. he starts at 7 a.m.

From the question to reach at 12 noon, he has 5 hours

∴ speed = 60/5 = 12 kmph