The speed of a boat in still water in 20 km/hr and the rate of current is 5 km/hr. The distance travelled downstream in 24 minutes is:
Choose the correct answer.
A) 10.6  B) 10.2  C) 10.8  D) 10.4  E) 10.0

Rationale: "speed downstream = ( 20 + 5 ) = 25 kmph time = 24 minutes = 24 / 60 hour = 2 / 5 hour distance travelled = time × speed = 2 / 5 × 25 = 10.0 km answer is e ."
Answer: E