White paint costs £2.80 per litre. Blue paint costs £3.50 per litre. White paint and blue paint are mixed in the ratio 3 : 2. Work out the cost of 18 litres of the mixture.
The ratio given tells us that our paint mixture of 18 litres consists of 3 + 2 = 5 parts.
Each part therefore consists of 18/5 = 3.6 litres of paint.
If we need 3 parts white paint, thats: 3 (parts) x 2.80 (£/litre) x 3.6 (litres/part) = £30.24 *
If we need 2 parts blue paint, thats: 2 (parts) x 3.50 (£/litre) x 3.6 (litres/part) = £25.20 *
Therefore the total cost of 18 litres is: 30.24 + 25.2 = £55.44
- Notice how the units cancel out here, so you know what you end up with is a cost!
VO
Related Maths GCSE answers
All answers ▸Solve the quadratic equation X^2+3X+2=0 by factorisation.
White paint costs £2.80 per litre and blue paint costs £3.50 per litre. White and blue paint are mixed in the ratio 3 : 2. How much does it cost to make 18 litres of this mixture?
solve x^2 + 5x +6 = 0
There are 720 boys and 700 girls in a school. The probability that a boy chosen at random studies French is 2/3 The probability that a girl chosen at random studies French is 3/5. Work out the number of students in the school who study French.