Final answer:
The price of inputs used to make the product is not assumed to be constant when drawing a supply curve. The elasticity of supply for the straight-line supply curve equation 4P = Q remains constant, so the elasticity as price rises from 3 to 4 will be the same as from 7 to 8.
Step-by-step explanation:
When drawing a supply curve for a product, various factors are assumed to be constant, but the price of inputs used to make the product is not one of them. The supply curve shows the relationship between the price of a good and the quantity supplied, assuming other factors are constant. Changes in input prices can lead to a shift in the supply curve. For example, if the price of inputs rises, it can shift the supply curve to the left, indicating a decrease in supply at any given price point.
Concerning the supply curve equation 4P = Q, to calculate the elasticity of supply as the price rises from 3 to 4, you would substitute the price into the equation to find the corresponding quantities supplied, and then use the formula for elasticity. Similarly, to find the elasticity as the price rises from 7 to 8, you would follow the same process. However, in the case of a straight-line supply curve (which is linear and has a constant slope), the elasticity of supply is constant at all points along the curve. This implies that the elasticity of supply when the price rises from 3 to 4 will be the same as when it rises from 7 to 8.