A ratio is a way of showing proportions of amounts. For example, if there are double the number of green marbles compared with the number of yellow marbles, then we can show this by writing 2:1. This would be read as: 'the ratio of green marbles to yellow marbles is two to one'. Two parts of the marbles are green and one part is yellow, but: what is 'part(s) of' as a fraction? It's easy: 2 + 1 = 3, so 2⁄3 are green, and 1⁄3 is yellow.
You would deal with other ratios in a similar way. This 11-plus Maths quiz is our easiest of the two on ratios. Give it a go and don't move on until you've got all ten questions correct. You might find having some paper and a pencil a handy addition. That way, you can write out (or even draw) the ratios.
Don't forget to read the helpful comment after each question. Good luck!