If John walks at the speed of 5 km/h, he reaches his office 7 minutes late.…
2025
If John walks at the speed of 5 km/h, he reaches his office 7 minutes late. However, if he walks at a speed of 6 km/h, he reaches his office 5 minutes early. How far is his office from his home?
- A.
9
- B.
8
- C.
10
- D.
6
Attempted by 69 students.
Show answer & explanation
Correct answer: D
Answer: 6 km
Explanation:
Let the distance to the office be x km.
Time taken at 5 km/h = x/5 hours (he is 7 minutes late), and time at 6 km/h = x/6 hours (he is 5 minutes early).
The difference in these times equals 7 minutes + 5 minutes = 12 minutes = 1/5 hour, so x/5 − x/6 = 1/5.
Compute: x(1/5 − 1/6) = 1/5 ⇒ x(1/30) = 1/5 ⇒ x = (1/5) × 30 = 6.
Therefore, the office is 6 km from his home.