A man can row 3.6 km/hr in still water. It takes him twice as long to row upstream as to row downstream. What is the rate of the current ?  Choose the correct answer.
A) 1.9 B) 1.7 C) 1.2 D) 1.5 E) 1.1

Rationale: "speed of boat in still water ( b ) = 3.6 km / hr . speed of boat with stream ( down stream ) , d = b + u speed of boat against stream ( up stream ) , u = b – u it is given upstream time is twice to that of down stream . ⇒ downstream speed is twice to that of upstream . so b + u = 2 ( b – u ) ⇒ u = b / 3 = 1.2 km / hr . answer : c"
Answer: C