Question 1199169
<br>
While the responses from the other two tutors are fine, there is no need to use a formal proportion or to find the constant of proportionality, as they did in their responses.  There is a much faster informal path to the answer.<br>
The value of x decreases by 25% or 1/4, which means the new value is 3/4 of the old value.<br>
Since the value of y is inversely proportional to the cube of x, the value of y changes by a factor of (4/3)^3 = 2.37 to 2 decimal places.<br>
An increase by a factor of 2.37 means a percent increase of<br>
100(2.37-1) = 100(1.37) = 137<br>
ANSWER: y increases by 137% when x decreases by 25%<br>