The formula for the time period oscillation of a spring is:
T = 2π√(m/k) where m is the mass of the object attached to the spring and k is the spring constant of the spring.
Multiplying m by 4 we have:
2π√(4m/k)
= 2π x 2√(m/k)
or 2 x (2π√(m/k)) or 2T.
Therefore, when object is four times as massive, then period will double.