CK12 - Geometry

Sincethereare 30 dancersand singersin all,

The numberof dancersis. The numberof singersis. It’s easy to check

theseanswers.The numbersof dancersand singershaveto add up to , and they haveto be in a

ratio.

Check:. The ratio of dancersto singersis , or to.

Proportions

Aproportionis an equation.The two sidesof the equationare ratiosthat are equalto eachother. Proportions
are oftenfoundin situationsinvolvingdirectvariation.A scaledrawingwouldmakea goodexample.

Example 3

Leo usesa scaledrawingof his barn.He recordedactualmeasurementsand the lengthson the scale
drawingthat representthoseactualmeasurements.

Barndimensions

Actuallength Lengthon scaledrawing

Dooropening feet inches

Interiorwall feet inches

Water line feet?

a) Sincehe is usinga scaledrawing,the ratio of actuallengthto lengthon the scaledrawingshouldbe the
sameall the time.We can writetwo ratiosthat shouldbe equal.This is the proportionbelow.

Is the proportiontrue?

We couldwritethe fractionswith a commondenominator. One commondenominatoris.

.

The proportionis true.

b) Dependingon how you think,you mighthavewrittena differentproportion.You couldsay that the ratio
of the actuallengthsmustbe the sameas the ratio of the lengthson the scaledrawing.

.