PROPORTIONS AND RATIOS

The following is a proportion. This proportion contains two ratios. Each side of the equal side is a ratio.  170 calories divided by 28 gm is one ratio and 340 calories divided by 56 gm is the other. (A calorie is a measurement of energy and is used to measure the energy value of food) Lets work with the following proportion:

170 CALORIES = 340 CALORIES

  28 gm            56 gm 

There are 170 calories in 28 gm of almonds.

In proportions if you cross multiply 28 x 340 it must equal 56 x 170. Does it?

This enables us to solve proportions with unknowns. For example how many calories in 58 gm of almonds?

170 CALORIES =   T CALORIES        

   28 gm          58 gm

Cross multiply 28 x T = 58 x 170 → 28T = 9860    T = 9860 ÷ 28 → T = 352.14 calories

240 ml (1 cup) of 2% milk fat contains 120 calories. How many calories in 257 ml?

120 CALORIES =   T CALORIES              

    240 ml       257 ml

240T = 120x257 → 240T = 30840 → T = 30840 ÷ 240 → T = 128.5 calories in 257 ml of milk

Find T in the following problems:

  1. 120 CALORIES   =  128.5 CALORIES

 240 ml                                                                                T ml

  2.   T CALORIES =  128.5 CALORIES

 250ml          257 ml

3.  120 CALORIES =  128.5 CALORIES

   T ml            257 ml

Is there a relationship between the denominators and the numerators?  answers

120 CALORIES =  257 ml

 240 ml        128.5 CALORIES    answer

WHEN YOU CROSS MULTIPLY IF THE PRODUCTS ARE EQUAL THEN THE EQUATION IS A PROPORTION. IS THE ABOVE A PROPORTION? WHY?

IS THE FOLLOWING A PROPORTION?

240 ml       =  257 ml

120 CALORIES    125.5 CALORIES  answer

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