Question

A motor boat takes 2 hours to travel a distance 9 km down the current; and it takes 6 hours to travel the same -distance against the current. The speed of the boat in still water and that ofthe current (in km/ hour) respectively are

• A. 3, 1.5
• B. 3, 2
• C. 3.5, 2.5
• D. 3, 1

Answer 1

The correct option is A 3, 1.5

Let the speed of boat in still water = x & speed of current = y
$\frac{a}{x+y}=2$
$9=2x+2y$ ........ (i)
$\frac{9}{x-y}=6$
$9=6x-6y$ ........ (ii)
Add (i) & (ii)
$4x=12$
$x=3km/hr$
$y=\frac{3}{2}km/hr$