uppose you have a stock of 40 tons of silicon, the marginal benefit of mining the qth ton of silicon is 30 0.75q, the marginal cost of mining a ton of silicon is $3, and the interest rate is 4%. (a) If today is the only time period, how much silicon should you mine now? (b) Suppose there are two time periods, today and tomorrow. How much silicon should you mine in each period? (c) Do you mine the same amount in each period? Why or why not