Question

A man can go downstream thrice as fast as he can go upstream between two specific points on a river. If the river flows at 8 kmph, what is the speed of the boat in still water?

• A. 14 kmph
• B. 15 kmph
• C. 16 kmph
• D. 18 kmph

Answer 1

The Correct Option is C

The objective is to determine the boat's speed in still water. Let this speed be denoted by \(b\) kmph. The provided information is:

• The speed downstream is \(b + 8\) kmph, with the river's speed being 8 kmph.
• The speed upstream is \(b - 8\) kmph.

The problem states that the downstream speed is triple the upstream speed:

\(b + 8 = 3(b - 8)\)

This equation models the relationship between the downstream and upstream speeds.

Solving the equation:

\(b + 8 = 3b - 24\)

\(b - 3b = -24 - 8\)

\(-2b = -32\)

Dividing by -2 yields:

\(b = 16\)

Consequently, the speed of the boat in still water is 16 kmph.