Ram covers a part of the journey at 20 kmph and the balance at 70 kmph taking…
2025
Ram covers a part of the journey at 20 kmph and the balance at 70 kmph taking the total of 8 hours to cover the distance of 400 km. How many hours has he been driving at 20 kmph?
- A.
2 hours
- B.
3 hours 12 minutes
- C.
2 hours 40 minutes
- D.
3 hours 20 minutes
Attempted by 8 students.
Show answer & explanation
Correct answer: B
Solution: Find the time spent at 20 km/h.
Let t be the hours driven at 20 km/h. Then the remaining time is 8 − t hours at 70 km/h.
Set up the distance equation: 20·t + 70·(8 − t) = 400.
Solve: 20t + 560 − 70t = 400 → −50t = −160 → t = 160/50 = 3.2 hours.
Convert 3.2 hours to hours and minutes: 0.2 hour = 0.2 × 60 = 12 minutes. So t = 3 hours 12 minutes.
Verification: distance at 20 km/h = 20 × 3.2 = 64 km; at 70 km/h = 70 × (8 − 3.2) = 70 × 4.8 = 336 km; total = 64 + 336 = 400 km.