Two planets A and B of radii R and 1 . 5R have densities ρ and...

The acceleration due to gravity is

$g = \dfrac{GM}{{R}^{2}} = \dfrac{4\piGRρ}{3} ⇒ g ∝ ρ \cdot R$

Thus, the ratio is

$⇒ \dfrac{{g}_{B}}{{g}_{A}} = \dfrac{1 . 5Rρ}{2ρR} = \dfrac{1}{2} \times 1 . 5 = 0 . 75 ⇒ \dfrac{{g}_{B}}{{g}_{A}} = \dfrac{3}{4}$