Suppose the instantaneous interest rate, as a function of time, is given by r(t)=7- 72-71 1+1 t20. Find the yield and discount curves, y(t) and DF(t), in terms of 71,72. What do the parameters r and 12 represent? Using r = 5% and r = 7%, plot the two curves r(t) and y(t) for t=0 30 on one plot. Plot the discount curve separately. If $100,000 is to be received in 15 years, determine its present value.