The speed of a boat in still water in 30 km/hr and the rate of current is 7 km/hr. The distance travelled downstream in 36 minutes is:	Choose the correct answer.
A) 18.4 km
B) 20.6 km
C) 21.4 km
D) 1111 km
E) 22.2 km

Rationale: "explanation : speed downstream = ( 30 + 7 ) = 37 kmph time = 36 minutes = 36 / 60 hour = 3 / 5 hour distance travelled = time × speed = ( 3 / 5 ) × 37 = 22.2 km answer : option e"
Answer: E