Question

What is the cost of 400g at £1.50 per 1/2kg

Answer 1

Well 0.5kg is an awkward number, so let's double £1.50 and 0.5kg to get £3 for 1kg, or 1000g.

So now, we can set up a proportion. (x is the cost)


`(3)/(1000) = (x)/(400)`.

Now we multiply 400 on both sides to get 'x' on its own.


`(3)/(1000)` ×
`400 = 1.2`

So now, we know the cost for 400g = £1.20.