Question 1197034
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I will guess that all of these direct and inverse variation problems that received responses from tutor @ewatrrr were posted by the same student.  So I will respond to this one post; but my response applies to all the other similar problems.<br>
In her responses, the other tutor always takes the given direct or inverse proportion and the given information to solve for the constant of proportionality, k.  If you were finding a formula based on given information which you were then going to use for multiple later calculations, then that is a good way to go.<br>
But in a problem like this, where you only need to find one other number based on the given information, all that work to find the value of k is unnecessary.  You only need to use the information about direct or inverse variation to solve the problem.<br>
The quick and easy path to the answer to this particular problem is this:<br>
The value of one of the variables changes from 75 to 25, a factor of 1/3; since the variation is direct, the value of the other variable changes by a factor of 1/3.<br>
ANSWER: 15(1/3) = 5<br>
Of course, if in another problem the variation was inverse and one of the variables changed by a factor of 1/3, the value of the other variable would change by a factor of 3.<br>