Which Alice?

Which Alice? Which Alice?

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Solutions to the Puzzles same number as Tweedledee), so he now has one more than half the total. If he wins the bet, then he will have two more than half the total. Also, he will then have two-thirds of the total (which is the same thing as having twice as many as Tweedledee), which is onesixth of the total more than half the total (because the difference between one-half and one-third is one-sixth). Therefore, one-sixth of the total more than half the total is the same thing as two more than half the total, so two rattles is the same thing as half the total. Therefore, the total number of rattles is twelve, so Tweedledum has seven and Tweedledee has five. Let us check: If Tweedledum loses, each will have six; if Tweedledum wins, he will have eight and Tweedledee will have four, so he will have twice as many as Tweedledee. HOW MANY BROTHERS AND SISTERS? There are four boys and three girls in the family. Tony has three brothers and three sisters; Alice has four brothers and two sisters. HOW MANY WERE WRONG? Exactly three right is the same thing as exactly one wrong, so the choice is between exactly three right and exactly two right. Now, it is impossible to get exactly three right, because if three are right, the fourth must also be right! Therefore, she got exactly two right. HOW MUCH LAND? A common wrong answer is 11 acres. If there had really been 11 acres, the tax collector would have taken away 1 1/10 acres (which is one-tenth of 11 acres), which would have left the farmer with 9 9/10 acres rather than 10 acres, so 11 acres cannot be the right answer. How does one find the right answer? Well, look at it this way: After one-tenth of the farmer's land had been taken away, he had nine-tenths left. So 9/10 of the original piece is 10 acres. This means 167

Solutions to the Puzzles<br />

same number as Tweedledee), so he now has one more than half<br />

the total. If he wins the bet, then he will have two more than half<br />

the total. Also, he will then have two-thirds of the total (which is the<br />

same thing as having twice as many as Tweedledee), which is onesixth<br />

of the total more than half the total (because the difference<br />

between one-half and one-third is one-sixth). Therefore, one-sixth<br />

of the total more than half the total is the same thing as two more<br />

than half the total, so two rattles is the same thing as half the total.<br />

Therefore, the total number of rattles is twelve, so Tweedledum has<br />

seven and Tweedledee has five.<br />

Let us check: If Tweedledum loses, each will have six; if<br />

Tweedledum wins, he will have eight and Tweedledee will have<br />

four, so he will have twice as many as Tweedledee.<br />

HOW MANY BROTHERS AND SISTERS? There are four boys<br />

and three girls in the family. Tony has three brothers and three<br />

sisters; <strong>Alice</strong> has four brothers and two sisters.<br />

HOW MANY WERE WRONG? Exactly three right is the same<br />

thing as exactly one wrong, so the choice is between exactly three<br />

right and exactly two right. Now, it is impossible to get exactly three<br />

right, because if three are right, the fourth must also be right!<br />

Therefore, she got exactly two right.<br />

HOW MUCH LAND? A common wrong answer is 11 acres. If<br />

there had really been 11 acres, the tax collector would have taken<br />

away 1 1/10 acres (which is one-tenth of 11 acres), which would<br />

have left the farmer with 9 9/10 acres rather than 10 acres, so 11<br />

acres cannot be the right answer.<br />

How does one find the right answer? Well, look at it this way:<br />

After one-tenth of the farmer's land had been taken away, he had<br />

nine-tenths left. So 9/10 of the original piece is 10 acres. This means<br />

167

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