Simple Harmonic Motion: Unknown Spring Constant

[JJackson09]

Homework Statement

A block attached to a spring with unknown spring constant oscillates with a period of 2.0 seconds. What is the period if a) the mass is doubled? b) the mass is halved? c) the amplitude is doubled? d) the spring constant is doubled?

Homework Equations

f=1/2pi(square root k/m)
f=1/T

The Attempt at a Solution

I understand when the period should increase and decrease but I am finding it hard to do the calculations. I cannot think of how to find the spring constant or the mass in order to fill in the missing parts of the equation.
Please Help!

 

[magwas]

Try using letters like m0, T0, and x0 for the unknowns.
Now when mass is doubled, you write
m = 2*m0
and substitue to the equations.