The gravitational force $F$ is given by $F = m E_G$, where $m$ is mass and $E_G$ is gravitational field intensity. Converting mass to kg: $m = 60\text{ g} = 0.06\text{ kg}$. Thus, $3.0 = 0.06 \times E_G$, which gives $E_G = \frac{3.0}{0.06} = 50\text{ N/kg}$.