= 64 N/m
According to Hooke's Law for a helical spring or an elastic material, extensional force is directly proportional to the distance the material has extended.
F = ke; where F is the extension force, k is the spring constant, and e is the distance extended.
Thus;
k = F/e
= 44N/0.69 m
= 63.768 N/m
= 64 N/m