Final answer:
To make peach squash with a 1:2 ratio of squash to water, and given 400ml of water, you will need 200ml of peach squash.
Step-by-step explanation:
To determine how much water is needed to make peach squash, we need to use the given ratio of 1:2.
This means that for every 1 part of peach squash, we need 2 parts of water.
Since we have 400ml of water, we can set up a proportion:
1 part peach squash / 2 parts water = x part peach squash / 400ml of water
Cross multiplying:
2(x) = 1(400)
2x = 400
x = 200
Therefore, you will need 200ml of peach squash.