also find marginal revenue. 6.4.2 Suppose the cost of producing an output level x of a good is x2 + 3x + 10. Find the marginal cost. 6.4.3 Suppose the supply function for tea is 9 = -1+ 2p, where p denotes price and q denotes quantity supplied. Find the elasticity of supply at the points where p = 1, 1.5 and 2. 6.4.4 Suppose the supply function for coffee is 9 = 3p-, where p denotes price and q denotes quantity supplied. Find the elasticity of supply at the points where p = 1, 1.5 and 2. Comment. 6.4.5 A country's imports M depend on its national income Y according to the relation M = 7+0.2Y +0.05Y2. Find the marginal propensity to import. Problems on Chapter 6 6-1. Find the equation of the tangent at the point on the curve y = x where x = 2. Find the value of y given by the tangent when x = 2 + h and use this to verify the small increments formula in this case. Find also the value of the function when x = 2 + h. Hence find the error when the curve near x = 2 is approximated by the tangent at x = 2. Calculate the error as a percentage of the true value if (i) h = 0.01, (ii) h = 1. 6-2. Sketch in the same xy-plane the graphs of y = 2 + 3x - 12 and its derivative. [To solve this problem correctly, you should use simple algebra and the methods of this chapter to obtain information about where the curves cross, and signs and magnitudes of slopes. You may find your answers to Exercises 5.4.4 and 6.3.3 helpful. Plotting is not permitted.]