Answers to the Brain Teasers

Here are the answers to the brain teasers I posted last week.


1. An Arab sheikh tells his two sons to race their camels to a distant city to see who will inherit his fortune. The one whose camel is slower wins. After wandering aimlessly for days, the brothers ask a wise man for guidance. Upon receiving the advice, they jump on the camels and race to the city as fast as they can.

What did the wise man say to them?


Answer : He told them to switch camels



2. There are ten tennis ball manufacturing machines. All but one manufacture the balls with exactly the same weight (100 gms each) . The faulty machine is manufacturing tennis balls with a weight of either 99 gms each or 101 gms each. You are allowed only one weighing to find the faulty machine and also tell if the faulty machine is manufacturing heavier balls or lighter balls.

How can you tell that?


Answer : Number the machines from 1 to 10. Take 1 ball from machine 1, 2 from machine 2, 3 from machine 3 etc and weigh them all at once. If all machines were functioning as they should, they would add up to 5500gms. If they weigh more than that, the faulty machine is manufacturing heavier balls. If they weigh less, it's manufacturing lighter balls. The difference between the weighed total and 5500gms will tell you which machine is the faulty one.