Exercise 5 Page 146

Practice makes perfect

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. part/whole=percent/100 ⇔ a/b=p/100We can find what number 2 % of 180 is by thinking about 180 as a whole and our missing number as the part. Let's substitute b= 180 and p= 2 into the formula and solve for a using the Properties of Equality.

a/b=p/100

SubstituteII

b= 180, p= 2

a/180=2/100

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Solve for a

ReduceFrac

a/b=.a /2./.b /2.

a/180=1/50

MultEqn

LHS * 180=RHS* 180

a/180* 180=1/50 * 180

FracMultDenomToNumber

a/180* 180 = a

a=180/50

MoveRightFacToNumOne

1/b* a = a/b

a=180/50

CalcQuot

Calculate quotient

a= 3.6

Knowing the value of a, let's look at the completed percent proportion. 3.6/180=2/100 Therefore, 2 % of 180 is 3.6.

We can find what percent 17 of 40 is by thinking about 17 as the part of a whole and 72 as the whole. Let's substitute a= 17 and b= 40 into the formula and solve for p using the Properties of Equality.

a/b=p/100

SubstituteII

a= 17, b= 40

17/40=p/100

▼

Solve for p

MultEqn

LHS * 100=RHS* 100

17/40* 100=p/100 * 100

FracMultDenomToNumber

a/100* 100 = a

17/40* 100=p