The ratio of the average density of pJupiter/pEarth?

Mass of Earth = ME
Mass of Jupiter = MJ
Volume of Earth = VE
Volume of Jupiter = VJ
Radius of Jupiter, RJ = 11.0 RE

(g on the surface of Earth) : (g on the surface of Jupiter) = 1 : 2.5
[G ME / RE²] : [G MJ / RJ²] = 1 : 2.5
[ME / RE²] : [MJ / (11.0 RE)²] = 1 : 2.5
[ME / RE²] : [MJ / (121 RE²)] = 1 : 2.5
[ME / RE²] : {[MJ / (121 RE²)] × 121} = 1 : (2.5 × 121)
ME : MJ = 1 : 302.5
MJ = 302.5 ME

ρ(Jupiter) / ρ(Earth)
= [MJ / VJ] / [ME / ME]
= [MJ / RJ³] / [ME / ME³]
= [(302.5 ME) / (11.0 RE)³] / [ME / ME³]
= 302.5 / 11.0³
= 0.227

2.5 = (Mj*G/(121re))*re/(Me*G)
G cross
2.5 = MJ/(Me121)
MJ = 302.5 Me
Vj = 11^3 = 1331Ve
ρj = Mj/Vj = 302.5 Me/1331Ve = 0.2273 Me/Ve = 0.2273 ρe

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