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Posted by Denis Borris on 19/9/2009, 5:21 am
A B C D want to get across a lake 312 miles across.
Swimming speeds in mph: A=4, B=8, C=12, D=16.
They have a motorboat that goes at 48mph.
But this boat can only take 2 persons.
D leaves first; 2 hours later, the other 3 leave, 2 of them in the boat.
After x hours, one of the 2 in boat jumps off and continues swimming;
at same time, driver turns boat around and goes back to pick up a swimmer;
after y hours, one of the 2 in boat jumps off and continues swimming;
at same time, driver turns boat around and goes back to pick up last swimmer.
During the last hour, a strong salmon decides to push the boat;
causes the boat to go 72mph during the last hour.
All 4 arrive on other side at same time, 16 hours after D left.
You need to find:
1- how many miles did the boat travel?
2- for how many hours did A swim?
3- how many miles did C swim?
4- how many hours was B in the boat?
NOTE: everything is in integer miles and hours (no fractions of nothing)
including drop-offs times and pick-ups times,
all speeds are constant, no interfering currents, no lost of time
getting in/out of boat, no loss of time doing boat u-turns,
no hanging on to the back of the boat or other such dishonest stuff;
in other words, no dirty tricks to make your life miserable.
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