Question

A boat takes 26 hours for travelling downstream from point A to point B and coming back to point C midway between A and B. If the velocity of the stream is 4 km/hr and the speed of the boat in still water is 10 km/hr, what is the distance between A and B?

• A. 210 km
• B. 185 km
• C. 140 km
• D. 168 km

Answer 1

Answer:

D. 168 km

Explanation:  Downstream speed = 10+4 = 14

Upstream speed = 10-4 = 6

Now total time is 26 hours

If distance between A and B is d, then distance BC = $\frac{d}{2}$

Now $\frac{distance}{speed} = time$, so

$\frac{d}{14} +\frac{(\frac{d}{2})}{6}= 26$

$\frac{13d}{84}=26$

Solve, d = 168 km