Lower Elementary
Question: A box containing 16 identical books, weighs a total of 36 pounds. If the box weighs 4 pounds, how much does each book weigh?
Answer: 2 pounds.
Note: The total weight of box + books = 36. 4 + weight of books = 36 pounds which means the 16 books weigh a total of 32 pounds. 32 ÷ 16 = 2 pounds.
Upper Elementary
Question: Sarah baked cookies for a bake sale. 1/2 of the cookies were chocolate chip, 1/3 were oatmeal raisin, and the other 8 were peanut butter. How many cookies did Sarah bake?
Answer: 48 cookies
Middle School
Question: Brian is going on a road trip in his van. When he leaves the house he has a half a tank of gas. After driving for 4 hours he used 80% of the gas in the tank. At that point he had 2 gallons of gas left. How many gallons of gas does the gas tank hold?
Answer
: 20 gallons
Note: Since the tank is only half-full when he leaves and after 4 hours he used 80% of the gas he has 20% of the half tank left. If 20% of the half tank his 2 gallons, then half a tank is 2 x 5 = 10 gallons (20 % = 1/5). Half a tank is 10 gallons which means a full tank is 20 gallons.
Algebra and Up
Question: A sphere is inscribed in a cube with a 216 cubic units. What is the volume of the sphere?
Answer: 36π cubic units ≈ 113.097 cubic units
Note: Since the sphere is inscribed in the cube, the radius of the sphere is equal to half of any side of the cube. To find the side length of the cube take the cube root of 216 = 6. That means the radius of the sphere is 3. Using the formula for the volume of a sphere 4/3•π•r3 = 36π cubic units ≈ 113.097 cubic units.
