Helen and her brother Donald perfected a substance they call Schtuck. This product works well on all smooth or textured walls, and can even hold enough weight for large picture frames without leaving any marks on the wall afterward. Helen is unsure how much she can charge for this product. She and Donald did some limited research, deciding that the feasible range would be $3$4 per small package of Schtuck. They plan to make the substance in their own home based on limited asset investments of $18,800. For the time being, they can make 5,000 small packages. (a) If Helen's desired return on her investment is 25%, what range of target cost can she incur on this product? (Round answers to 2 decimal places, e.g. 15.25.) The range of target cost is between \$ and \$ per unit