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

Question

Please help i don't understand

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?

Answer 1

a) Your equation will be C = kN

b) To find k, we plug 40 in for C, the cost, and 32 in for N, liters of fuel. Then we solve for k.

40 = k(32)

40/32 = k

5/4 = k

Now that we know that k = 5/4, we substitute 5/4 for k in the equation every time since it is a CONSTANT.

c) In this part we want to find the cost of 50 liters, so we plug 50 in for N and solve for C

C = (5/4)(50)

C = $62.50

d) The limitation for this problem would be you can't exceed the fuel capacity of the car.