Craner, think of this: If you had a hundred people, and 65 of them were walkers, and the remainder cyclists, how would you express this as 1, a percentage, and 2, a ratio?

When you're doing ratios keep in mind the fact that the ratio just tells you that every however many people or things (add the two numbers in the ratio, e.g. 65+35=100) so many will be one and so many the other (e.g. for every hundred people 65 walk and 35 cycle). This means that the numbers themselves are irrelevant, it's just their relative proportions, which are given for each number by dividing it by the sum of both numbers. So 65:35 is the same as 130:70 is the same as 1300:700 is the same as 13:7 is the same as 0.4095:0.2205 because each and every time their relative proportions are the same and therefore 65/(65+35)=0.65=65% and 130/200=0.65=65% and 13/20=0.65=65% and 0.4095/0.63=0.65=65%. Per cent literally means "every one-hundred"--as in, "every 100 people" 65 walk--and so a percentage is already a ratio, just one that's so standard you use and understand it without ever thinking or worrying about it.

When you get stuck with anything in maths, try to make the problem as simple as possible and lay out what you already know for certain. Like in Q2, you know that 65% of your group are walkers so that every hundred people in the sample 65 walk. You can multiply those numbers up however you like--multiply both by any number (the same number!) and their proportions stay the same. 65% of 1000 and 65% of 100 is still 65% even though 0.65*1000=650 and 0.65*100=65. There are as many ways of expressing this ratio (65:35=13:7, etc) as there are real numbers but the *ratio* *between the two numbers* is always the same.