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7. Practice Find the limit. Use l'Hospital's Rule where appropriate. lim 3 (In ac) 3 Limit:a- A fence is to be built to enclose a rectangular area of 310 square feet. The fence along three sides is to be made of material that costs 5 dollars per foot, and the material for the fourth side costs 14 dollars per foot. Find the dimensions of the enclosure that is most economical to construct. Dimensions: A 17 foot ladder is leaning against a wall. If the top slips down the wall at a rate of 2 ft/s, how fast will the foot be moving away from the wall when the top is 13 feet above the ground? The foot will be moving at y; ft/s. Find the following limit. Notes: Enter "DNE" if limit Does Not Exist. (1 point) A tank contains 5000 L of pure water. Brine that contains 30 g of salt per liter of water is pumped into the tank at a rate of 25 L/min. The concentration of salt after t minutes can be shown to be given by: 3075 C(t) : 200 + t What happens to the concentration as t > oo? lim C(t) = t>oo - An open box is to be made out of a 11inch by 16inch piece of cardboard by cutting out squares of equal size from the four corners and bending up the sides. If the box needs to be at least 1 inch deep, and no more than 3 inches deep, nd the absolute maximum and absolute minimum volumes. Maximum volume: a; Minimum volume: y; 2. Practice An ostrich farmer wants to enclose a rectangular area and then divide it into three pens with fencing parallel to one side of the rectangle (see the figure below). There are 790 feet of fencing available to complete the job. What is the largest possible total area of the three pens? Largest area = (include units