Given (x is number of items) Demand function: d(x)=630-0.5x^2 Supply Function: s(x)=0.2x^2 Find the equilibrium quantity: Find the consumers surplus at the equilibrium quantity :

x= 30 CS = S [acy ) - scy)]dy 30 S [ [ 6 30 - 0. 5 x ]- [o. 2x ] ]]dy 30 = [ [ 630 - 0. 7 xy ]dy = 630 x [y] - 0- 7 43730 = 630 X30 - 0. 7 x 90 0X30 = 18900 - (210 x 30] = 18900 - 6300 (s = 12 600 ". The consumer surplus at the equilibrium quantity is approximately 12600