A market supply curve has three prices $2.50, $3.00 and $3.50 with a quantity supplied of 6 tonnes at the price of $2.50, 9 tonnes at $3.00, and 12 tonnes at $3.50.

a. Is this supply curve a straight line?

This curve is a straight line because it has a constant slope of 0.334.

b. What is the price elasticity of supply, es, between prices $2.50 and $3.00 and between prices $3.00 and $3.50?Do not round your interim calculations before obtaining the final solution (i.e. do not clear your calculator). In each case, express the number to two decimal places and do not include a positive or negative sign (i.e. 1.67, not -1.7 or +1.667).

The price elasticity of supply isbetween prices $2.50 and $3.00, and isbetween prices $3.00 and $3.50.

c. Based on your answers to parts (a) and (b), must a supply curve with a constant slope have a constant numerical elasticity?

A supply curve whose slope varies must have a constant supply elasticity.