Question: Little Johnny is walking home. He has $300 he has to bring home to his mom. While he is walking a man stops him and gives him a chance to double his money. The man says "I'll give you $600 if you can roll 1 die and get a 4 or above, you can roll 2 dice and get a 5 or 6 on at least one of them, or you can roll 3 dice and get a 6 on at least on die. If you don't I get your $300."
What does Johnny do to have the best chance of getting home with the money?
Answer: He just doesn't take the bet. This gives him a 100 percent chance of getting the money home. If he takes the bet with 1 die he has a 50 percent chance of winning. If he takes the bet with 2 dice he has about a 56 percent chance of winning. If he takes the bet with 3 dice he has about a 42 percent chance of winning.
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.