1. The problem statement, all variables and given/known data Consider an item that is initially sold at a market price of $10 per unit. Over time, market forces push the price toward the equilibrium price, $20, at which supply balances demand. After 6 months, the price has increased to $15. the Evans Price Adjustment model says that the rate at which the market price changes is proportional to the difference between the market price and the equilibrium price. 2. Relevant equations N/A 3. The attempt at a solution dp/dt = 20-p, where p=market price in dollars and t=time in months ∫dp/20-p = ∫1dt ln (20-p) = t+c 20-p = e^(t+c) 20-p = e^t*e^c 20-p = Ae^t, where A=e^c p = 20-Ae^t 10 = 20-Ae^0 10 = 20-A A=10 Now that I've solved for A with the initial condition, I have hit a roadblock. I'm pretty sure my initial setup of this problem is off. When I substitute 15 in for p, I get a negative t, which is impossible. Please help.