Percents, fractions, ratios, and decimals are all ways to show "part of a whole".

We can convert between these various quantities. In particular, if we can find a fraction that represents the {exercising population} / {total population} then you can compute the decimal representation. Once you have the decimal representation you can find the percentage by moving the decimal place two units to the right.

[assuming the exercising population given is the 'adult' exercising population]