The first step is to find the area of the bulletin board--this will let you know how much space you have to cover.
The problem tells you the bulletin board has sides that are 4 and 3 feet, making this a rectangle. The formula for finding the area of a rectangle is:
A = lw therefore, multiply 4x3 to find your area, which is 12 ft (it's important to note what measurement you're using).
The index cards are 4x6 inches, so use the same formula to find the area of an individual index card.
4x6=24, so one index card takes up 24 inches of space.
To find out how many you can get on the board, you will divide the space of one index card by the space of the board. HOWEVER, the board is currently measured in feet, and our cards are measured in inches. We have to convert the board's area into inches.
12 inches = 1 foot. We have 12 ft of board. So multiply 12x12 to get the area of the board in inches.
12x12=144 < there is 144 inches of open space on the bulletin board.
Now jump back to the area of one index card: 24. Now we must divide 144 by 24 to see how many card will fit.
144/24=6 < this is the number of cards that can fit on the bulletin board.
Answer: 6 cards are needed to cover the board.
