To solve this problem it is necessary to use the concepts of Force of a spring through Hooke's law, therefore,
Where,
k = Spring constant
x = Displacement
Initially our values are given,
PART A ) With this values we can calculate the spring constant rearranging the previous equation,
PART B) Since the constant is unique to the spring, we can now calculate the force through the new elongation (0.38cm), that is
Therefore the weight of another person is 265.79N.