Question

A man can row at 5 km/h in still water. If the river flows at 1 km/h and it takes him 1 hour to row to a place and return, what is the distance he rows to the place?

• A. 1 km
• B. 2 km
• C. 2.4 km
• D. 3 km

Hint:

For river boating problems, account for stream speed in both directions and sum the times.

Answer 1

The Correct Option is C

Speed downstream = \( 5 + 1 = 6 \) km/h, upstream = \( 5 - 1 = 4 \) km/h. 
Let distance to place = \( d \) km. Total time = 1 hour: 
\[ \frac{d}{6} + \frac{d}{4} = 1 \] \[ \frac{2d}{12} + \frac{3d}{12} = 1 \Rightarrow \frac{5d}{12} = 1 \Rightarrow d = \frac{12}{5} = 2.4 \] Thus, the answer is 2.4 km.