Answer:
3.12 pound.
Explanation:
Energy due to weight, w, of the spring = 0.9 ×
will be represented by

If energy stored by the spring is 12 joules.
Then weight of the spring will be
m'g = w' = 0.9

= 0.9 × 3.46
= 3.12 pounds
The approximate weight of the spring is 3.12 pound.