Math problem 83 or something, Real mathematicians can't count Options

[Raijinili]

Say that when you take pistachios, you take ten per handful, you eat the unshelled ones, take off the shells of the shelled ones, and drop the newly unshelled ones back into the bowl.
If you had a bowl of 100 shelled pistachios, how many grabs would it take to eat them all?

[jcdietz03]

after thinking about this for a bit...

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isn't it 20? On each handful you grab ten pistachios. You need to grab each one twice in order to eat it. You need to make 200 grabs total. You make 10 grabs per handful, so you need 20 handfuls.

After thinking about this some more, I think you need 21 handfuls:
Take a simpler case where u have 20 in your bowl. Theoretically, you'd need 4 grabs.
After round 1 you have 10 shelled and 10 unshelled.
Let's say for round 2 you picked 5 shelled and 5 unshelled. After round 2 you have 5 shelled and 10 unshelled.
Let's say for round 3 you picked 2 shelled and 8 unshelled. After round 3 you have 3 shelled and 4 unshelled.
You pick them all up for round 4, but at the end of the round you have 3 unshelled still. You need to make a fifth grab in order to eat them.

This post has been edited by jcdietz03: Feb 2 2008, 11:05 PM