To calculate the correct dose of metoclopramide from a 5 mg/5 ml stock solution, you would need to divide the prescribed dose of 15 mg by the concentration of the stock solution, which is 5 mg/5 ml. This calculation would give you a result of 3 ml. Therefore, you would need to administer 3 ml of the 5 mg/5 ml metoclopramide solution per dose in order to achieve the prescribed dose of 15 mg.