Problem of the Week - Middle School - April 25, 2021 to May 1, 2021

Middle School: 

Question: 24-karat gold is 100% pure gold. How many ounces of pure gold are there in a 15 pound, 16-karat gold bar? 

Answer: 160 ounces

Solution: 16–karat gold is 16/24 pure gold, or 2/3. Since two thirds of the gold bar is pure gold, that means that there are 15 × 2/3 = 10 pounds of pure gold. There are 16 ounce in a pound, so 10 pounds of pure gold is the same as 160 ounces of pure gold.