Let S_t be the current price of a stock that pays no income. Let r_BID be the interest rate at which one can lend/invest money, and r_OFF be the interest rate at which one can borrow money. Both rates are continuously compounded. Assume r_BID lesstanorequalto r_OFF, except in (a). Assume r_BID > r_OFF. Find an arbitrage portfolio. Verify it is an arbitrage portfolio. Use a no-arbitrage argument to prove the forward price with maturity T for the stock satisfies the upper bound F(t, T) lesstanorequalto S_te^r_OFF(T-t). Use a no-arbitrage argument to prove a similar lower bound for the forward price. Assume the stock has bid price S_t, BID and offer (or ask) price S_t, OFF. The bid price is the price for which you can sell the stock. The offer price is the price for which you can buy the stock. How do the upper and lower bounds in (a) and (b) change? Prove these bounds using no-arbitrage