Displacement is your answer :)
Answer:
389 kg
Explanation:
The computation of mass is shown below:-

Where K indicates spring constant
m indicates mass
For the new time period

Now, we will take 2 ratios of the time period




= 0.889 kg
Since mass to be sum that is
= 0.889 - 0.500
0.389 kg
or
= 389 kg
Therefore for computing the mass we simply applied the above formula.