Final answer:
The equilibrium interest rate can be found by setting the money demand equal to the money supply and solving for the interest rate. In this case, the money supply is $2,000 and the price level is fixed at $100. The money demand function is (M/P)d = 800 - 50r, where r is the interest rate in percent.
Step-by-step explanation:
The equilibrium interest rate can be found by setting the money demand equal to the money supply and solving for the interest rate.
In this case, the money supply is $2,000 and the price level is fixed at $100. The money demand function is (M/P)d = 800 - 50r, where r is the interest rate in percent.
Substituting the given values into the equation, we have 2,000/100 = 800 - 50r. Simplifying this equation gives us 20 = 800 - 50r.
Rearranging the equation to solve for r, we have -50r = -780, and dividing both sides by -50 gives us r = 15. Therefore, the equilibrium interest rate is 15%.