Exercise 3 Page 335

The percent proportion is a proportion that sets the ratio of a part of a whole equal to the ratio of a percent out of 100. We can represent a is p percent of wwith the given proportion. part/whole=percent/100 ⇔ a/w=p/100We can find what percent 12 of 30 is by thinking about 12 as the part of a whole and 30 as the whole. Let's substitute a= 12 and w= 30 into the formula and solve for p using the Properties of Equality.

a/w=p/100

SubstituteII

a= 12, w= 30

12/30=p/100

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Solve for p

MultEqn

LHS * 100=RHS* 100

12/30* 100=p/100 * 100

FracMultDenomToNumber

a/100* 100 = a

12/30* 100=p

MoveRightFacToNum

a/c* b = a* b/c

12* 100/30=p

Multiply

Multiply

1200/30=p

CalcQuot

Calculate quotient

40=p

RearrangeEqn

Rearrange equation

p= 40

Knowing the value of p, let's look at the completed percent proportion. 12/30=40/100 We found that 12 is 40 % of 30.

Checking Our Answer

Checking Our Answer

We can use a model to check our answer.