A pie crust recipe calls for 2 1/4 cups of flour per batch. If you make 2 batches, how many cups of flour are needed?

• A. 4 1/2 cups
• B. 6 cups
• C. 5 cups
• D. 4 cups

Answer: (A)

Doubling the amount you use is the idea here: two batches means twice as much flour as one batch. Add the amounts: 2 1/4 cups plus 2 1/4 cups equals (2+2) + (1/4+1/4) = 4 + 1/2 = 4 1/2 cups. So you need 4 1/2 cups of flour. You can also see this by converting to improper fractions: 2 1/4 is 9/4; doubling gives 18/4 = 9/2 = 4 1/2. The other options don’t match doubling: they’d be too little or too much.