A builder can obtain concrete from any of four suppliers.
Supplier W charges £12 per ton for the concrete and a fixed delivery charge of £50 regardless of the quantity ordered.
Supplier X charges £14 per ton including delivery.
Supplier Y charges £11.5 per ton for the concrete and a fixed delivery charge of £100. However, for orders in excess of 40 tons delivery is free from supplier Y.
Supplier Z charges £11 per ton for the concrete, £2 per ton delivery charge and a fixed delivery charge of £20.
(a) Prepare a worksheet and a graph that will indicate, for a range of order amounts, the total cost of concrete ordered from each of the four suppliers.
(b) Prepare a worksheet and a graph that will indicate, for a range of order amounts, the cost per unit of concrete ordered from each of the four suppliers.