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Identify the percent of change as an increase or a decrease then find the percent of change. Round to the nearest tenth of a percent if needed

question #1  120 pounds to 180

question #2 10ft to 8ft

Jan 30, 2018

#1
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1.

180  is bigger than  120  so this is an increase.

120  increased by what percent of  120  is  180   ?

Let  x  be the percent of increase.

120  +  120x   =   180

120x   =   60

x   =   60/120   =   0.5   =   50/100   =   50%

120  increased by  50%  of  120  is  180 .

2.

8  is smaller than  10  so this is a decrease.

10  decreased by what percent of  10  is  8    ?

10 - 10x  =  8

-10x  =  -2

x   =   -2 / -10   =   20 / 100   =   20%

10  decreased by  20%  of  10  is  8 .

Jan 30, 2018
#2
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Thanks for that good answer, hectictar.......here's another way to do this......

We can actually  use the same "formula" to figure both of these

% increase / decrease   =    (  l New Value - Old Value l  / Old Value  x 100 ) %

So...for the first one we have

(   l  180 - 120 l  /  120  x 100) %  =

(  l   60  l   /  120   x 100 ) %  =

(  60  / 120  x 100 ) %   =

( 1 / 2  x 100 ) %  =

50%  increase

For the second one, we have

(  l  8  - 10  l  /  10   x 100 ) %    =

(  l -2 l  / 10  x 100 ) %  =

(  2  / 10  x 100 ) %  =

( 1 / 5  x 100 ) %  =

20%  decrease   Jan 30, 2018