By David Pleacher
Question: Does a pound of gold or a pound of feathers weight more?
Answer: The feathers. A pound of feathers is measured in avoirdupois weight, in which one pound equals 16 ounces. Precious metals are measured in troy weight, in which one pound equals 12 ounces.
However, the ounces are not measured in the same way. In avoirdupois weight, one ounce = 437.5 grains. In troy weight, one ounce = 480 grains.
So, one pound of feathers weighs (16)x(437.5 grains) = 7,000 grains. One pound of gold weighs (12)x(480 grains) = 5,760 grains.
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.