f.4 econ

a)The equilibrium price will drop as the supply of Brand A cameras increases due to the new saving method.

b)As there is a fall in the price of developing and printing films, the production cost of producing films decreases. So the producers will be willing to produce more films to earn more money and the supply of films will increase. As the supply of films increase, the equilibrilium price will drop.

c)Since Brand A cameras and other brands of cameras are substitutes, if there is a fall in the price of other brands of cameras, the demand for Brand A cameras will decrease. So the equilibrium price will decrease.

d)As camera is a kind of superior good, when the income of the citizens increase, there will be an increase in the demand for Brand A cameras. As the demand for Brand A cameras increase, the equilibrium price will increase.

Diagrams:
http://tinypic.com/view/?pic=4321gt3

(a) The new method saves the cost of production, and the sellers become more willing to supply at every price level. So the supply curve shifts to the right. This lowers the price and raises the quantity transacted of Brand A cameras.

(b) Developing and printing films and cameras are compliments because they must be used together to take photos. So the fall in price of developing and printing films will raise the demand for cameras. Both the price and quantity of Brand A rises.

(c) Cameras of different brands are substitutes. When price of other brands falls, people are more likely to switch from Brand A to other lower-priced brands, causing a fall in demand for Brand A cameras. The fall in demand will lower both the price and the quantity of Brand A cameras.

(d) If Brand A cameras are normal / superior goods, the increase in real income will raise the demand, which raises both the price and quantity transacted of Brand A cameras.
If Brand A cameras are inferior goods, the increase in real income will lower the demand, which lowers both the price and quantity transacted of Brand A cameras.