Final answer:
To express the amount of white fabric to coloured fabric as a ratio, convert the units first. June uses 0.1 cm of white fabric for every 1 mm of coloured fabric, resulting in a ratio of 1:10.
Step-by-step explanation:
To express the amount of white fabric to coloured fabric as a ratio, we need to convert the units first so they are the same. June uses 1 cm for every 10 cm of white fabric.
Since 1 cm is equivalent to 0.1 mm, we can say that June uses 0.1 cm of white fabric for every 1 mm of coloured fabric.
Therefore, the ratio of white fabric to coloured fabric is 0.1:1, which can also be written as 1:10 in its simplest form.