There are 10 sets of coins.You know how much the coins should weigh.You also know that all the coins in one set of 10 are exactly a hundredth of an ounce off,making that entire set of 10 coins a tenth of an ounce off.You are also told that all the other coins weigh the correct amount.You are allowed to use an extremely accurate digital weighing machine only once.How do you determine which set of 10 coins is faulty?
Mark the sets from 1 to 10. Take one coin from the first set, 2 from the second, 3 from the third and so on, until all 10 from the last set. Now weigh the coins. Weight of these coins minus (55xcorrect weight) will give you the difference. Divide by 1/100 to get the set number which contains the deficient coins
ReplyDeleteThe answer is correct.But suppose the machine can work only upto the weight of 50 of the normal -not defective- coins.How will you then proceed.?
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