In this item, we are asked to determine the length at which the spring will be stretched given that a fish is attached to one of its end. To answer this, first, we must calculate for the weight of the fish.
Weight = (3.15 kg)(9.8 m/s²)
Weight = 30.87 N
Then, divide the calculated weight by the given force constant to determine the length.
Length = (30.87 N)/(855 N/m) = 0.036 m