Multiple choice

A goes to his office from his home at the speed of 12 km/hr. If he goes with 5/6 of his usual speed then he will reach late by 20 minutes. Find the distance between his home to office ?

  1. 4 km

  2. 15 km

  3. 20 km

  4. 25 km

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Usual speed = 12 km/h. Reduced speed = (5/6) × 12 = 10 km/h. Time ratio is inverse of speed ratio: t_slow/t_fast = 12/10 = 6/5. The 20-minute (1/3 hour) delay equals (6/5 - 1)t_fast = t_fast/5. So t_fast = 5/3 hours. Distance = 12 × 5/3 = 20 km.