Subject: General Aptitude · Chapter: Boats and Streams · Exam: · Marks: · Difficulty:
There is a road beside a river. Two friends started from a place A, moved to a temple situated at another place B and then returned to A again. One of them moves on a cycle at a speed of 12 km / hr, while the other sails on a boat at a speed of 10 km / hr. If the river flows at the speed of 4 km / hr, which of the two friends will return to place A first?
Answer
Answer (as printed):
Explanation
Clearly, the cyclist moves both ways at a speed of 12 km/hr. So, average speed of the cyclist = 12 km/hr. The boat sailor moves downstream @ (10 + 4) i.e., 14 km/hr and upstream @ (10 - 4) i.e., 6 km/hr. So, average speed of the boat sailor $=\left(\frac{2 \times 14 \times 6}{14+6}\right)$ km/hr $=\frac{42}{5}$ km/hr $=8.4$ km/hr. Since the average speed of the cyclist is greater, he will return to A first.
Explanation as extracted from the printed page; notation may be imperfect.