Chapter 4.1, Problem 65E

Supply and demand for T-shirts. Suppose that the supply and demand equations for printed T-shirts for a particular week are

$\begin{array}{cc}p=0.7q+3& \text{Price-supply}\text{equation}\\ p=-1.7q+15& \text{Price-demand}\text{equation}\end{array}$

where $p$ is the price in dollars and $q$ is the quantity in hundreds.

(A) Find the supply and demand (to the nearest unit) if T-shirts are $\text{\$}4$ each. Discuss the stability of the T-shirt market at this price level.

(B) Find the supply and demand (to the nearest unit) if T-shirts are $\text{\$}9$ each. Discuss the stability of the T-shirt market at this price level.

(C) Find the equilibrium price and quantity.

(D) Graph the two equations in the same coordinate system and identify the equilibrium point, supply curve, and demand curve.