Paul is mixing coloured paint. He wants to make a certain tone of olive. The mixing recipe is below. Quantities needed for four litres of paint: blue, 800 millilitres; red, 900 millilitres; yellow, 1700 millilitres; grey, 600 millilitres. Paul needs to make 50 litres of this paint. How much does he need of each colour?
The quantities we’ve been given are enough for four litres of paint. We need to find out how to scale this up to 50 litres of paint. To work out the amount we’ll need to multiply each colour by, we need to divide 50 by four.
Dividing by four is the same as halving and halving again, or we could complete this on a calculator. Half of 50 is 25, and half again is 12.5. This means if we multiply four litres of paint by 12.5, we’re scaled up to the 50 litres of paint we require. We’ll therefore need to multiply the amount for each colour by 12.5.
800 multiplied by 12.5 is 10000 millilitres. 900 multiplied by 12.5 is 11250 millilitres. 1700 multiplied by 12.5 gives us 21250. And 600 multiplied by 12.5 is 7500. The units on each answer line are in millilitres. That means then we need 10000 millilitres of blue, 11250 millilitres of red, 21250 millilitres of yellow and 7500 millilitres of grey.
Had we been required to convert these measurements into litres, we would’ve had to recall the fact that one litre is equal to 1000 millilitres. To change from millilitres into litres, we divide by 1000. So we would’ve had to divide each of our measurements for our colours by 1000 to give us the measurements in litres.