Doubt from Simple Harmonic Motion

I have some confusion here... the energy in the (b) part is coming out to be 2.5 by this:

in c) part I used the fact that total energy in SHM is conserved and used 1/2 kA^2 = 2.5 which gave approx 22 cm...but when I checked for equated 1/2 k (2)^2= 1/2kA^2..why didn't they take they equate it to the initial total energy?

Isn't it given answer 2.5 for (b)