Uddalak.Banerjee
BAN USERI think the answer provided by Anonymous on october 11,2011 is the right one.As the ropes each will burn for one hour..SO Rope R1 be burned at both ends and R2 be burned at one end.SO after half and hour R2 will reach its half too.Now if we light the other end of R2 it will burn out in 45 minutes .
- Uddalak.Banerjee October 12, 2011Well i think the question says that each rope burns for 1 hour.SO in that case what i feel the answer should be that Take Rope R1 and burn it at both ends and take another Rope r2 And burn it on only one end .Now as R1 keeps burning for half hour(as two ends are burned and considering rope to be homogeneous).Now as R2 has been burning along with R1 when the Rope R1 is burnt out in half an hour it must have reached half its length! So then now if we burn the other end of the rope R2 too..then it will completely burn out in 45 minutes!!.I think this should be the answer.
- Uddalak.Banerjee October 12, 2011
As per the question i think the above answer is perfect.But thinking a little out of the box since it is a bridge and hence must be over a river.So if we strictly count only the time taken to cross by them and not the time taken by the torch to pass from one side of the bridge to the next then the answer comes out to be 9 minute( person of 9 minute and 7 minute together) +2 minute( person of 1 minute and 2 minute together)= 11 minute total time to pass the bridge.
- Uddalak.Banerjee October 12, 2011BUt here however we are neglecting the water current and the time it takes to move the torch in water