Answer:
T = [tex]1/2\pi \sqrt (k/m) \\[/tex] so period of mass spring system becomes 2 times w.r.t original problem.
Explanation:
[tex]T =1/2\pi \sqrt(k/m)\\[/tex] so when k = 1 is replaced by 4 it means it becomes
k" = 4k
[tex]T' = 1/2\pi \sqrt(k'/m)\\T' = 1/2\pi \sqrt(4k/m)\\T' = 2(1/2\pi\sqrt(k/m)\\)\\T' = 2T[/tex]