Gravitational Force between three forces

[DRC12]

1. Homework Statement [/b]
There's a 20kg ball and two 10kg balls 20cm above it. One of the 10kg balls is 5cm to the right of center and the other is 5cm to the left of center. What is the net gravitational force on the 20kg ball

2. Homework Equations [/b]
F=GMm/R²3. The Attempt at a Solution [/b]
M=20kg, m=10kg, G=6.67E-11 and R=√(.20²+.05²)=.206m
\SigmaF_x=0; because the 10kg ball are equal distances away from the 20kg ball along the x-axis
\SigmaF_y=2*(((6.67*10^-11*10*20)/(.206²))*(.2/.206))=6.1*10^-7
I know the answers supposed to be 3*10^-7

 

[TSny]

Your work looks correct to me.

 

[DRC12]

All right thanks I'm just going to assume the books wrong it wouldn't be the first time