Problem 5. World reserves of chromium are about 800 million tons, and current usage is about 2 million tons per year. If growth in demand for chromium increases exponentially at

a constant rate of 2.6 percent per year, how long would it take to use up current reserves? Suppose the total resource is five times current reserves; if the use rate continues to grow at 2.6 percent, how long would it take to use up the resource?