13. Consider the following events: Scientists reveal that consumption of oranges decreases the risk of diabetes and, at the same time, farmers use a new fertilizer that makes orange trees more productive. Illustrate and explain what effect these changes have on the equilibrium price and quantity of oranges.

Al. Say that the demand schedule for a good is given by QD = 20 - 2P and the supply schedule is given by qs = _io + 4R

a. Graph the demand and supply curves, showing the x- and y-intercepts for each.

b. Determine the equilibrium price and quantity.
A2. The demand and supply functions for hockey sticks are given by QD = 286 - 20P Qs = 88 + 40P

a. Graph the supply and the demand curves, clearly showing the intercepts and indicating the slopes of the two curves.

b. Determine the equilibrium price and quantity of hockey sticks.

c. Suppose that both the men's and the women's teams win Olympic gold medals, causing an increase in the demand for hockey sticks across the country to QD = 328 - 20P. What impact does this have on the price of hockey sticks and the quantity sold?
A3. Suppose that the demand curve for concert tickets is linear. When the price of a ticket is $5.00, the number of tickets purchased is 1000; when the price of a ticket is $15.00, the number of tickets purchased is 200. Find the slope of the demand curve.
A4. At a price of $320 per tonne, the supply of wheat in Canada is 25 million tonnes and the demand is 26 million tonnes. When the price increases to $340 per tonne, the supply increases to 27 million tonnes and the demand decreases to 22 million tonnes. Assume that both the demand and supply curves are linear.

a. What is the equation for the demand curve for wheat?

b. What is the equation for the supply curve for wheat?

c. Using these equations, what is the equilibrium price and quantity of wheat?
A5. Market research has revealed the following information about the market for chocolate bars: The demand schedule can be represented by the equation QD = 1600 — 300P, where QDis the quantity demanded and P is the price. The supply schedule can be represented by the equation Qs = 1400 + 700P, where Qs is the quantity supplied.

a. Calculate the equilibrium price and quantity in the market for chocolate bars.

b. Say that in response to a major industry ad campaign, the demand schedule for chocolate bars shifted to the right, as represented by the equation QD = 1800 — 300P. What happens to the equilibrium price and quantity of chocolate bars in this case?

c. Returning to the original demand schedule, say that the price of cocoa beans, a major ingredient in the production of chocolate bars, increased because of a drought in sub-Saharan Africa, a major producer of cocoa, changing the supply schedule to Qs = 1100 + 700P. What happens to the equilibrium price and quantity in this case?