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What is the fewest number of pairs you need to test to guarantee you can get the flashlight on?

+2 votes
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You have a flashlight that takes 2 working batteries. You have 8 batteries but only 4 of them work.

What is the fewest number of pairs you need to test to guarantee you can get the flashlight on?

posted Oct 7, 2014 by Sandeep Otari

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