The positive health benefits of apples lead to a shift in John's demand curve because there was a change in a parameter of demand that was not price. A parameter is any important factor that influences the behavior of consumers. The parameters of demand are the consumer need for the good, income of the consumer, quality and availability of the good, the price of the good, of the substitute goods and of complementary goods, expected future price of good and publicity. .
2a. The increase of public transportation fares will lead to an increase in the entire demand curve for cars (D1 to D2 in the graph). The fares become more expensive therefore decreasing people's desire to use public transportation because it is unaffordable. This demand decrease in the public transportation industry will lead to an increase demand for cars because cars are the only substitute goods for public transportation. Therefore increasing the quantity of cars produced (Qe1 to Qe2 on the graph) which will in turn result in higher price (Pe1 to Pe2 on the graph).
2b. If the price of gas was to increase there would be a decrease in the entire demand curve (D1 to D2 on the graph) for cars. The expensive price of gas would result in people not driving their own cars or potential buyers waiting until the price of gas lowers to buy a car. Less demand for cars would mean the quantity of cars produced would decrease (Qe1 to Qe2 on graph) therefore causing a drop in the price of cars (Pe1 to Pe2).
2c. Steel is a necessity in manufacturing cars. If the price of steel were to increase then this would lead decrease in the entire supply curve (S1 to S2 on the graph). Since the price of steel is more expensive then the car company would manufacture less quantity of cars (Qe1 to Qe2 on the graph), however, because steel is expensive the car manufacturing company would increase the price of cars in order to be able to afford the steel (Pe1 to Pe2 on the graph).
