Question
There are two stationary boats (A and B) on a river. B is downstream from A. At 9AM, a raft starts floating downstream from A to B. The still water speed of the raft is 0 kmph. At the same time, a boat starts out from B to A and meets the raft in 5 hours and then reaches A. It immediately returns to B. Find the time that the boat and the raft reached B, if it is given that they both reached together?
Answer: Option C
:
C
Option ( c)
Speed of river= S kmph
Speed of boat= B kmph
In 5 hours, the boat would have traveled 5(B-S)km and the raft would have traveled 5S km
The raft has to cover 5(B-S)km at S km/hr speed
The boat has to cover 5S km at (B-S) kmph and (5S+5B-5S) km at (B+S) kmph speed
5(B−S)S=5SB−S+5BB+S
It will take 52 hours= 7.07 hours after 2 pm.
Answer = option c
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:
C
Option ( c)
Speed of river= S kmph
Speed of boat= B kmph
In 5 hours, the boat would have traveled 5(B-S)km and the raft would have traveled 5S km
The raft has to cover 5(B-S)km at S km/hr speed
The boat has to cover 5S km at (B-S) kmph and (5S+5B-5S) km at (B+S) kmph speed
5(B−S)S=5SB−S+5BB+S
It will take 52 hours= 7.07 hours after 2 pm.
Answer = option c
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