If Rahul rows 15 km upstream in 3 hours and 21 km downstream in 3 hours, then…
2024
If Rahul rows 15 km upstream in 3 hours and 21 km downstream in 3 hours, then the speed of the stream is
- A.
5 km/hr
- B.
4 km/hr
- C.
2 km/hr
- D.
1 km/hr
Attempted by 14 students.
Show answer & explanation
Correct answer: D
Key calculations:
Upstream speed = distance/time = 15/3 = 5 km/hr.
Downstream speed = distance/time = 21/3 = 7 km/hr.
Let boat speed in still water be b and stream speed be s. Then b - s = 5 and b + s = 7. Subtracting gives 2s = 2, so s = 1 km/hr.
Final answer: 1 km/hr.