A forestry company is replanting an area after timber has been harvested. It is comparing two nitrogen fertilisers.
| Fertiliser | Mass of one sack (kg) | Percentage of nitrogen by mass (%) | Cost per sack (£) | Delivery charge for one order (£) |
|---|---|---|---|---|
| M | 500 | 20 | 160 | 20 |
| N | 400 | 30 | 204 | 30 |
Calculate the cost of each fertiliser per tonne of nitrogen. Ignore the delivery charges.
The company needs to buy enough fertiliser to provide at least 240 kg of nitrogen. It can only buy whole sacks.
Calculate which fertiliser gives the lowest total cost, including delivery.
136 exam-style questions on OCR GCSE Chemistry 6.1 Improving processes and products, covering 6.1.1 Extracting metals industrially and by electrolysis, 6.1.2 Life cycle assessment and recycling, 6.1.3 Biological methods of metal extraction, 6.1.4 The Haber process and the production of fertilisers, 6.1.5 Alloys and their uses, 6.1.6 Corrosion and its prevention, 6.1.7 Comparing and selecting materials, and 6.1.8 Industrial conditions, rate and position of equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.