4.7 PROPO

RTIONAL

RELATIONSH

IPS

I CA N I D

E N T I FY P

R O P O R T I ON A L

R E L A T I ON S H I P

S AN D F

I ND C

O N S T A N T S OF

P R O P O R T I ON A L I T

Y BY U

S I NG P

R O P O R T I ON S .

USING A TABLE• The table shows Keisha’s distance during

a bike-a-thon. Is there a proportional relationship between time and distance?

• Compare the ratios of distance and time.

• Are they proportional?• Well, if you use cross products…• 52=52 so yes!

USING A GRAPHThe graph show’s the same data. Keisha’s

distance over time. What is her speed in miles per hour?

Find her distance when the time is 1 hr.

If the line passes through(0,0) and (2, 13) then it must go through (1, 6.5)

So the speed is 6.5 mphThis is the unit rate.

CONSTANT OF PROPORTIONALITYValue of the ratio of quantities

in a proportional relationship.

Equivalent to the unit rate.

WRITING AN EQUATION USING CONSTANT OF PROPORTIONALITYA recipe that calls for 3 tbsp of

butter uses 9 tsp of butter. Find the number of teaspoons, t, in T tablespoons.

The ratio of so if we cross multiply we get t=3T

ASSIGNMENTODDSp. 167 #7-19