Question: 13. The annual demand for dog biscuits at Dogwatch Security amounts to 1690 kg. The cost of the manager going to collect a supply of dog biscuits in her company is reckoned to be £40 per trip. The cost of storing the biscuits is estimated to be £8 per kilogram per year. The dog biscuits come in sealed packs and last indefinitely. How many kilograms of dog biscuits should the manager collect at a time to minimize their total stock costs?