As part of a DIY project, Jake wants to use wood cladding to cover a wall measuring 2.3m high and 2.9m wide. Cladding comes in packs of 5 planks, with each plank measuring 129cm long and 19.4cm wide. Each pack costs £13.50 plus VAT at 20%.
a) How many packs will Jake need to buy to cover the wall area?
b) What will be the total cost of the cladding for Jake’s wall?
A familiar style of GCSE question on area of rectangles. Students need to decide to calculate the area of the wall and the area of a pack of planks (taking care to convert to a common unit before multiplying by 5). It is important to stress to students that given the high marks awarded for a question of this type, even if the overall method proves too difficult for them, method marks will be awarded for working out any of the following:
- Area of the wall
- Area of one plank
- Area of a pack of planks
- Total price of one pack of planks
Discussions regarding rounding up or down to the nearest pack are also useful.
Teachers could extend the learning by considering:
- Asking students to work out wastage of material, given the rounding to the nearest full pack.
- Introduce the idea of ‘online purchasing’ which has a delivery charge. Ask students to factor this into a new total. Delivery must also have VAT calculated on it.
- Introduce a ‘10% off all ex-VAT prices’ offer for a bank holiday. Ask students to calculate how much could be saved if the cladding is bought at this lower price.
- Introduce a ‘time to cut and apply one plank’ (maybe 10-15 mins), and ask students to give an estimate for the time to complete the job.