Sarah Johnson has a balloon payment of $75,000 due in 4 years. What is the present value of that amount if the money earns interest at 12%. 23. Quarterly? 24. Continuously? 4 29. The instantaneous rate of change in demand for U.S. lumber since 1970 (t = 0) , in billions of cubic feet per year, is given by Q (t) = 12 + 0.006t Ost 50 Find the area between the graph of Q' and t axis over the interval [35, 46]