Question 1163167: four adults and four children need to cross a river in a rowing boat. Can you determine how to get everyone across, and how many crossings are needed, given the following information?
1.All adults weigh the same
2.Each child weighs half as much as an adult
3.The boat can only carry the weight of one adult
4.The boat must have someone in it to row it!
(a) What if there were 8 adults and 4 children?
(b) What if there were 200 adults and 4 children?
(c) What if there were n adults and 4 children?
Answer by ikleyn(52794)   (Show Source):
You can put this solution on YOUR website! .
The cycle to transfer one adult across the river is this:
a) Two boys, A and B, cross first in the boat.
b) Then boy B returns back alone, leaving boy A on the other bank of the river.
c) Then 1-st adult cross the river alone in the boat.
d) Then boy A returns back alone.
After these crossings, one adult is transferred to the opposite bank.
Repeat this cycle as many times until all 4 adults are transferred to the opposite bank of the river.
After that, transferring boys is a simple problem, which you can analyse by similar manner on your own, without my help.
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