I have a question in an assignment that says "Estimate the central pressure of 0.5, 1.0, and50 solar mass stars. Compare these pressures to the central pressure of the sun" I can estimate for the sun using the Hydrostatic equilibrium equation: dP/dr = -GM(r)p(r)/R^2 since I know Mass of sun is 1 solar mass and I know the radius. However, when I want to calclulate the central pressure of the other solar mass stars.. I don't know the radius.. So is there a way for coming up with that? The assignment doesn't give me any more information. Should I assume the same radius as the sun?