Question

Jeff is baking a cake. The recipe says that he has to mix 32 grams of vanilla powder to the flour. Jeff knows that 1 cup of that particular vanilla powder has a mass of 128 grams. He added 2/3 of a cup of vanilla powder to the flour. Should Jeff add more vanilla powder to make the exact recipe, or did he go over and by what amount?

He needs to add 1/4 of a cup
He went over by 5/12 of a cup
He went over by 1/4 of a cup
He needs to add 5/12 of a cup

Answer 1

The amount of vanilla the recipe calls for is what fraction of a cup?
The recipe calls for 32 grams.
1 cup is 128 grams.
32 grams is what fraction of 128 grams?

Answer 2

1/4

Answer 3

Great.
The recipe calls for 1/4 cup.
Jeff added 2/3 cup.
What is more, 2/3 or 1/4?

Answer 4

2/3

Answer 5

Correct.
Now we know he added too much and does not add to add more.
The question remaining is how much extra did he add?
For that we subtract:
2/3 - 1/4

Answer 6

To subtract fractions, you need a common denominator.
What is the LCD of 3 and 4?

Answer 7

5/12

Answer 8

Correct.

Answer 9

so the went over by 5/12