Question 1177223
<br>
Using the formal definition of inverse proportion, the time t and the speed s are related by<br>
{{{t = k/s}}}<br>
where k is the constant of proportionality.<br>
All three responses you have received to this point use that constant k in one way or another to solve the problem.<br>
For quick computation, however, it is easier to work with this equivalent statement of inverse proportion:<br>
{{{t*s = k}}}<br>
That form of the statement for inverse proportion says that the product of time and speed is a constant, so there is no need to determine the proportionality constant, or to use it in your computations.  You can solve the problem (or any similar problem involving inverse proportion) using the idea that the product of the time and speed for one swimmer is equal to the product of the time and speed for the other swimmer.<br>
Then the whole problem becomes just this:<br>
{{{200*3 = 120*x}}}
{{{600 = 120x}}}
{{{x = 5}}}<br>
ANSWER: 5 feet per second<br>