ANSWER:
3.26 kg
STEP-BY-STEP EXPLANATION:
Let there b 2 bodies of mass M and m:
[tex]\begin{gathered} F=\frac{G\cdot M\cdot m}{r^2} \\ \text{ In this case M = 2m, therefore:} \\ F=\frac{G\cdot2m\cdot m}{r^2}=\frac{G\cdot2m^2}{r^2} \\ F=\frac{G\cdot2m^2}{r^2} \\ \text{ solving for m:} \\ m^2=\frac{r^2\cdot F}{2\cdot G} \\ m=\sqrt[]{\frac{r^2\cdot F}{2\cdot G}} \\ \text{ Replacing:} \\ m=\sqrt[]{\frac{1.21^2\cdot9.71\cdot10^{-10}}{2\cdot6.67259\cdot10^{-11}}} \\ m=3.26\text{ kg} \end{gathered}[/tex]The mass is 3.26 kg
