Question

Donna is making a cookie recipe that calls for 1 ¾ cups of sugar. However, when she

goes to take out the measuring cups she can only find the one-half cup measuring cup. How many one-half cups will she need to fill to get the correct amount of sugar for her cookie recipe?

Answer 1

3 and 1/2 half-cups

Explanation:

We are asked to find the number of half-cups that will equal 1 3/4 cups.

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Let the desired number be represented by n. Then we require ...

n × 1/2 = 1 3/4 . . . . some number of 1/2-cups will give 1 3/4 cups

Using a common denominator, we have ...

n × 2/4 = 7/4

Multiplying by the inverse of the coefficient of n gives ...

n × 2/4 × 4/2 = 7/4 × 4/2

n = 7/2 = 3 1/2 . . . . . simplify

That is, Donna can measure 1 3/4 cups of sugar by using her 1/2-cup measure 3 times, and filling it half-full for the final 1/4 cup she needs.

She needs 3 1/2 half-cups to get the correct amount.