Two cars, same road — Aptitude Question
Two cars, same road: Two cars cover the same distance, one at 45 km/h and the other at 60 km/h. Answer and worked solution on CodeKairo.
- Topic: Time, Speed & Distance
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 90 seconds
Question
Two cars cover the same distance, one at 45 km/h and the other at 60 km/h. The slower takes 1 hour longer. What is the distance?
Options
- 120 km
- 150 km
- 180 km
- 200 km
Show the answer and the worked solution
Correct answer: C. 180 km
Worked solution
- d/45 − d/60 = 1.
- Common denominator 180: 4d/180 − 3d/180 = 1 → d/180 = 1.
- d = 180 km.
Answer: 180 km.
The idea
Difference of times equals the stated delay. The common denominator of the two speeds is usually the distance itself, which is a handy check.
Shortcut. Distance = (product of speeds ÷ difference of speeds) × time gap = (2,700 ÷ 15) × 1 h = 180 km.
Common trap. Subtracting the denominators — taking 1/45 − 1/60 as 1/15 — gives d = 15 km; the true difference is 4/180 − 3/180 = 1/180, so the one-hour gap is d/180.