Gravitational potential energy released in core collapse

[creepypasta13]

Homework Statement

Estimate the gravitational potential energy released in the collapse of a 1.2 solar-mass core from an initial density of 10^9 g/cm^3 to a final 10^15 g/cm^3.

Homework Equations

The Attempt at a Solution

The book doesn't provide much guidance on this. I was thinking of using q= 3/5 assuming the density is constant. Then manipulate M^2/R to Rho*(M)*(R^2)*(4pi/3). And plug in the values for Rho that are given and substitute 1.2 for M. But there's no mention of what the radius is. Do I just use the solar-radius?

Never mind the above. I think I computed it correctly.

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[edgepflow]

Maybe you can apply: PE = - GM / r.

Use mass = density X volume. Mass is given (1.2 X mass of sun). Densities are given.

Volume = (4/3) Pi r^3. You can find the change in radius.