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Two walls of our gallery need to be painted (one has a doorway). You can see them here. Each wall needs two coats of paint. The painter knows that 1 litre of paint will cover 10mof the wall. How much paint do you need to buy?

Remember to use your calculator.

	Clue

	Answer

You need to buy 30 litres of paint. If you said 15 litres you were forgetting that you need two coats.

First you needed to work out how much wall you have to paint (or the surface area of the walls). You do this by multiplying the length of the wall by its height, and adding together the figures for the two walls. Remember to subtract the space for the door (again just multiple its height by its width and take it away from your wall total).

• Wall 1: 4.5m x 15m = 67.5m
• Wall 2: 4.5m x 20m = 90m
• Door: 2.5m x 3m = 7.5m
• Wall 2 minus door: 90m– 7.5m = 82.5m
• Wall 1 plus wall 2 = 150m

Now to find out how many litres of paint you need you should divide your total wall by 10 (because you know that 1 litre will cover 10 sq metres of wall).

• 150m2 10 litres = 15 litres

This figure is how many litres you need for one coat, so just multiply it by 2 to get the total for 2 coats.

• 15litres x 2 coats = 30 litres

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