Speed of a boat in standing water is 9 kmph and the speed of the stream is 6 kmph. A man rows to place at a distance of 210 km and comes back to the starting point. The total time taken by him is:
Choose the correct answer:
A) 92 hours  B) 24 hours  C) 84 hours  D) 48 hours  E) None
Sol.   Speed upstream = 3 kmph; Speed downstream = 9 kmph.   ∴ total time taken = [210/3 + 210/9] hours = 84 hours.   Answer 84 hours
<result>C</result>
Speed of a boat in standing water is 9 kmph and the speed of the stream is 6 kmph. A man rows to place at a distance of 210 km and comes back to the starting point. The total time taken by him is: