Question

Laura is baking a cake. The recipe says that she has to mix 64 grams of chocolate powder to the flour. Laura knows that 1 cup of that particular chocolate powder has a mass of 128 grams. She added 2/3 of a cup of chocolate powder to the flour. Should Laura add more chocolate powder to make the exact recipe, or did she go over and by what amount?

A) She went over by 1/3 of a cup
B) She needs to add 1/3 of a cup
C) She needs to add 1/6 of a cup
D) She went over by 1/6 of a cup
Please show me how you got your answer :D

Answer 1

She went over by 1/6 of a cup because 64 is half of 128 and 2/3 is greater then 1/2 

Answer 2

Answer: Using operations with fraction to solve the problem, Laura went over by 1/6 of a cup (option D).

Solution:

The recipe says that she has to mix 64 grams of chocolate powder to the flour. Like 1 cup of that particular chocolate powder has a mass of 128 grams, 64 grams represent:

64/128=(64/64)/(128/64)=1/2 of a cup of chocolate

She added 2/3 of a cup of chocolate powder to the flour. If we compare:

2/3=0.67 > 1/2=0.5

Then, she went over by:

2/3-1/2=[(2(2)-3(1)]6=(4-3)/6=1/6 of a cup