Suppose a speculator takes the long side of five wheat futures contracts at a futures price of F0 = $5.190 (per bushel). Each contract calls for delivery of 5,000 bushels of wheat on the delivery date. Calculate the total dollar amount that is added to or taken away from the investors margin account for each of the following sequence of prices: F1 = $5.230; F2 = $5.285; F3 = $5.250.