84 calories in 3/4 cup of cereal.how many calories in 7cups?

Question

I am in need of this help for an assignment that I am involved in in school.

your help would be greatly appreciated

Answer 1

I personally would start by converting 3/4 cups to a decimal so that you can set up a proportion to easily solve this problem. (*Note: this is not a necessary step to solving this problem, but I find that plugging in decimals to a calculator / multiplying fractions can be more difficult compared to decimals--there is more room for error when multiplying fractions, but it's up to you as far as how you choose to approach this problem.) 

 

3/4 cups = 0.75 cups 

 

Then, set up a basic proportion, making sure to keep "like" units on the same "side" (numerator or denominator) of your fractions. Which could look something like this: 

 

(84 calories)/(0.75 cups) = (x calories)/(7 cups) 

 

Then solve for "x" (or whatever variable you choose), disregarding units until your final answer, (which will give you the amount of calories in 7 cups of this cereal.) 

 

84*7 = 0.75x

x=784 calories (per 7 cups of cereal)

Answer 2

Hi Anthony,

 

We can set up this proportion  (equivalent ratios) to solve for our unknown quantity:

    calories : cups = calories : cups

 

Plugging in our three known values and our one unknown value (x) into this proportion:

    84 calories : 3/4 cup = x calories  : 7 cups

 

Substituting the equivalent decimal (0.75) for the fraction (3/4):

    84 : 0.75 = x : 7

 

Now we can get our equation by setting the cross products of our proportion equal to each other and then solve it for our unknown value (x):

    (84)(7) = (0.75)(x) 

    0.75x = 588

    x = 588/0.75

    x = 784 calories in 7 cups

 

The concept of a proportion is key to the solving of ratio problems.

 

Thanks for submitting this problem and glad to help.

 

God bless, Jordan.