Exercise 4 Page 125

Let's start by recalling that 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 We want to find the number that is 12 % of 72, which means that we want to find the part. Let x represent the part. x/72=12/100 Now we can solve the proportion we got for x. Let's do this by using the fact that the cross products of any proportion are equal.

x/72=12/100

CrossMult

Cross multiply

x* 100= 72* 12

Multiply

Multiply

100x=864

Finally, we will use the Division Property of Equality to get the value of x.

100x=864

DivEqn

.LHS /100.=.RHS /100.

100x/100=864/100

CancelCommonFac

Cancel out common factors

100x/100=864/100

SimpQuot

Simplify quotient

x=864/100

CalcQuot

Calculate quotient

x=8.64

RoundDec

Round to 1 decimal place(s)

x≈ 8.6

We got that x≈ 8.6 is a solution to the proportion. This means that 12 % of 72 is equal to about 18.6.