Question

A recipe for a cake needs 2 1/4 cups of cake. You are making 1/2 of the recipe. How many cups of flour do you need?

Answer 1

1 & 1/8 cup of flour

Explanation:

A = half of 2 = (1/2)*2 = 1

B = half of 1/4 = (1/2)*(1/4) = (1*1)/(2*4) = 1/8

C = half of (2 & 1/4)

C = (half of 2) + (half of 1/4)

C = A+B

C = 1 + 1/8

C = 1 & 1/8 cups

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An alternative is to first convert the mixed number 2 & 1/4 to an improper fraction using the formula below

a & b/c = (a*c + b)/c

2 & 1/4 = (2*4+1)/4

2 & 1/4 = 9/4

Then multiply this by 1/2

(9/4)*(1/2) = 9/8

And convert back to a mixed number

9/8 = (8+1)/8

9/8 = 8/8 + 1/8

9/8 = 1 + 1/8

9/8 = 1 & 1/8

we get the same answer either way

Answer 2

4.5 or 1 1/8

Explanation:

2 1/4 is a full box to back 1/2 of the flour you need to divide 2 1/4 in half

Half of 2 is 1 & half of 1/4 is 1/8