# Eureka Smartphones

## The Situation

Luke wants to buy a cell phone plan that does not cost him much. He comes across two plans in The Eureka Smartphone. The first cell phone plan cost \$48 monthly for unlimited minutes of usage. The second cell phone plan costs \$10 monthly and \$0.05 per minute. Now the question is which plan to buy? To make the decsion, Luke decides to make a scattor plot on the number of minutes and its cost for both Plans.

## Identifying the Variables

Independent Variable : cost
Depented Variable : number of minutes used

## Equation

Plan 1

y=45

The slope is equal to 0

hence the line will be horizontal, with the y- intercept of 45

Plan 2

y=0.5x+10

Slope= Δy / Δx

= 20-15/20-10

= 5/10

= 0.5

y= 0.5x + b

since line passes through (10,15). substitute x= 10 and y= 15

15=0.5(10)+b

15 = 5 +b

15-5=b

10=b

y=0.5x+10

## Point of interaction

\$45= 0.5x + \$10
\$45 - \$10= 0.5x
\$35= 0.5x
\$35/0.5= x
70 = x

Point of interaction (70 minutes, \$45)

## Significance

In conclusion, Luke chooses plan 2 until he reaches 70 minutes, than he will switch to plan 1 because will be cheaper than plan 2.