Bonus

Have you finished early? Are you ready for an extra challenge?

Here is a revised version of the situation modelled in the section ‘Graphing in GeoGebra’.

Jack is employed as a salesperson for ElectroCorp. His job is to try to sign households up to ElectroCorp as their electricity supplier. He receives a base rate of $30 per day plus $50 for every household that he signs up.

Model this situation in GeoGebra by following these steps.

1. Draw up a table of values showing how Jack’s total pay depends on the number of households he signs up on a given day.

2. Use your table to find an equation expressing the relationship between these variables.

3. Examine how the equation would change in each of these situations.

   1. Jack’s base rate is increased to $40 per day but his commission doesn’t change.

   2. Jack’s commission is increased to $70 per day but his base rate doesn’t change.

4. Use GeoGebra to model this situation with a graph. Include two sliders: a ‘commission’ slider, as in the previous activity, and a 'base' slider which should vary between 0 and 60.

5. Do you agree with the following statement?
   'If we subtract Jack’s base rate from his total pay, the result is directly proportional to the number of households he signs up.'
   Explain why you agree or disagree, referring to your graph in Geogebra.