# Question: the cost c of filling a car with fuel is...

###### Question details

The cost, C of filling a car with fuel is directly proportional to the number, N litres of fuel purchased.

a) Write the variation equation relating C, N and the constant of variation, k

b) If the cost of 32 litres of fuel is $40 find the value of k.

c) Find the cost of filling the car with 50 litres of fuel. d) What is the limitation of this linear model?