Barb is going to cover a rectangular area 8 feet by 10 feet with rectangular paving blocks that are 4 inches by 8 inches by 2 inches to make a flat patio. What is the minimum number of paving blocks she will need if all the paving blocks will face the same direction? (Note: Barb will not cut any of the paving blocks.)
A. 80
B. 360
C. 601
D. 960
E 1,213
Think of the blocks as fractions of 1 foot: 4 inches is 1/3, 8 inches is 2/3. Say you set it up with 4 inches as the width and 8 inches as the length–so the 8 coincides with the 10 and the 4 coincides with the 8. Since 4 inches is 1 foot for every 3 blocks you just have to multiply 8 by 3 to get the number of blocks she will need vertically–24. Then you do the same for the 10 foot length. You know that you need 2 blocks for every 3 feet so you multiply by 10 by 3/2 to get the amount of blocks that she will need horizontally–15. Lastly you take both of those numbers, 24 and 15, and multiply them to get the total number of blocks she will need. 360.