1.  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 ?
A. Cyclist
B. Boat Sailor
C. Cannot be determined
D. None of these

Answer: Option A

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 :

= 2 x 14 x 6/14 +6 km/hr.

= 42/5 km/hr = 8.4 km/hr.

Since the average speed of the cyclist is greater, he will return to A first.