Answer:
The potential energy stored in a spring is directly proportional to the square of the displacement (compression or extension) of the spring. Therefore, by compressing the spring a distance 3d instead of d, the potential energy stored in the spring would be:
(3d)^2 / d^2 = 9.
This suggests that by compressing the spring a distance 3d, the spring would have 9 times more potential energy compared to compressing it a distance d.
In other words, compressing the spring 3 times further results in a potential energy increase of 9 times.