How do I answer this word math problem

Question

The nutrition information on the cereal box says that a 1/2 cup
serving provides 120 calories and 6
grams of dietary fiber. At that rate, find how many calories and grams of fiber are in a 2/3 cup
serving?

Answer 1

Do this as a proportions problem for calories and for fiber, separately.

 

Calories:

 

1/2 cup → 120 cal

2/3 cup → x

 

The proportion is (1/2) / (3/2) = 120 / x

 

x = (2/3)(120) / (1/2) = 160 cal

 

2/3 cups provides 160 cal

 

Fiber:

 

1/2 cup → 6 g

2/3 cup → y

 

(1/2) / (2/3) = 6/y

 

y = (2/3)(6) / (1/2) = 8 g

 

2/3 cup provides 8 g of fiber