Block hanging from spring when a second block is added

[dtesselstrom]

A block hangs in equilibrium from a vertical spring. When a second identical block is added, the original block sags by 3.00 cm. It wants to know the oscillation frequency of this problem.
So far I tried solving for F=-ky with F being 2m*g and y equal to .03. I solved for k and plugged that into T=2pi sq root of m/k this however said it was wrong. Any information on how to approach this would be nice.

 

[OlderDan]

A block hangs in equilibrium from a vertical spring. When a second identical block is added, the original block sags by 3.00 cm. It wants to know the oscillation frequency of this problem.
So far I tried solving for F=-ky with F being 2m*g and y equal to .03. I solved for k and plugged that into T=2pi sq root of m/k this however said it was wrong. Any information on how to approach this would be nice.

The 3cm sag comes from adding 1m. How much do you think the spring is streteched from its natural length with the 2m hanging on it?