Algebraic equations involving Percent*

 

In mathematics, as in everyday language, we use statements to communicate ideas.  Here
 we are translating into algebraic equations.  In order to write these equations, you must
look carefully at the wording – changing one word or its position can significantly change
 both the meaning of the sentence and its algebraic translation.

EXAMPLE:
 x is 8% more than some y

X = 1.08y (1 gives you the y and .08 gives you the more)

 

Translate the following sentences into an equation with two variables.

 

1)  x is 15% of y                                   2) x is 15% larger than y

 

 

 

3) x is 15% smaller than y                     4) x is 35% larger than some y

 

 

 

5) The median sales prices for a new single-family home in 1997 had risen by roughly
70% over the price in 1987.  (Let x represent the price in 1997, and y represent the price in 1987).

 

 

 

6) The increase in the perimeter of a rectangle if its length of L feet is increased by 25%
 and its width of W feet is increased by 10%.

 

 

 

7) The decrease in the circumference of a circle if its diameter of d meters is shortened by
12%.

 

 

 

8) One number is 55% smaller than a second number.

 

 

9) One number is five more than 20% of another number.

 

 

10) One number is two less than 18% of a second number.

 

 

 

* adapted from College Algebra, Houghton Mifflin, 1992

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