You are on your way to your friend's house. You decide to carry 2 apples to your friend. To get to their house, you must pass across 8 gates. At each gate, the keeper will take half the amount of apples you have and return one apple back. The question is, how many apples should you carry at the beginning?
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2$\begingroup$ if there was a lateral thinking tag: start with zero apples, walk through the gate, throw your apple over the next gate, then you will have two apples! $\endgroup$– Yout RiedSep 10, 2018 at 19:48
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$\begingroup$ And that's why I didn't include it, cuz I know some people have an infinitely broad imagination! $\endgroup$– Wais KamalSep 10, 2018 at 19:53
3 Answers
You need
2 apples.
This is because
Each gatekeeper will take one apple (half of two) and return one to you, meaning you keep the same number of apples through each gate.
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1
I am not sure if it's this easy. But here's a try.
You need to carry only 2 Apples. At each gate, the keeper will take half the amount i.e. 1 apple and will return it. At the end, you are still left with 2 apples.
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$\begingroup$ Close one! I think I barely beat you in, but great answer nonetheless! :D $\endgroup$– El-GuestSep 10, 2018 at 15:49
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$\begingroup$ That's correct, but @El-Guest answered first :) $\endgroup$ Sep 10, 2018 at 15:49
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Well,
Let’s work backwards: (2 apples - 1) * 2 = 2. Therefore, you only need to bring 2 apples.
Also,
You could only bring one apple, and walk through the gates and back. Then you should have around 1.8 apples. Then leave the .8 and repeat for infinite apples! :P
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$\begingroup$ @Wais Kamal And neither did the gatekeepers, apparently! $\endgroup$ Sep 10, 2018 at 15:54