Question: A man wants to have a party in thirty-one days where he will be serving his 1000 barrels of wine. The only problem is that one of his enemies poisoned one of the barrels. The poison kills any man who drinks any of the wine in about 30 days, give or take a few hours. The man has 10 plants that are also killed by the poison in 30 days and can be used to test the wine. How can identify the single poisoned barrel of wine?
Answer: To do this the man must create 1000 unique groups from the 10 plants in which each group has between 1 and 10 plants, and give each plant wine from a different barrel. He can then throw away the barrel of wine that corresponds to the group that died from the wine.
Question: Man walks into a store and says to the shop owner: “I will spend $10 in your store if you double the amount of money I now have in my pocket.” Store owner agrees; doubles his money; he spends $10 and leaves. He repeats this at 2 more stores. When he leaves the 3rd store he has $0 dollars. How much money did he have in his pocket when he walked into the first store?
Answer: You have to solve this starting with the last store. This means he walked into the 3rd store with $5, had it doubled to $10 and spent the whole $10. He entered the 3rd store with $5.00. He spent $10, so he had $15 after his money was doubled. $15 / 2= Means he had $7.50 when he entered the 2nd store. He left the 1st store with $7.50. He spent $10 so he had $17.50 after his money was doubled; $17.50 divided by 2. So, he started out with $8.75 when he walked into the first store.