$2\mathrm{.}15$ Cost function; opportunity cost; relevant costs LO$2$

Yummy Yoghurt sells yoghurt cones in a variety of natural flavours. Data for a recent month follow:

Revenue $$9000$

Cost of ingredients $$4500$

Rent $1000$

Store attendant salary $2300$

$7800$

Profit $$1200$

Required

$($a$)$ Categorise each cost as fixed or variable.

$($b$)$ Create a cost function.