A motor boat can row at a speed of 10 km hr in still water. If the river is flowing at 3 km hr and it takes 48 hours for a round trip (i.e. from place A to B and B to A). The distance between A and B is :

218.4 km

The correct answer is Option (2) → 218.4 km

Upstream speed = $10 - 3 = 7\, km/hr$

Downstream speed = $10 + 3 = 13\, km/hr$

$\frac{d}{7}+\frac{d}{13}=48$ [Given]

$\frac{20d}{91}=48$

$d=\frac{4568}{20}=218.4\,km$