Use P=F/A
As P is equal at both point as these points are connected by same liquid and at same hight
so P1 = P2
so
F1/A1 = F2/A2
so F1= 100N
A1 = Pi * r^2 (round because diameter is given)
F2 = M*g = 1000*10 = 10000
A2 = Pi* r2 = pi*1^2 (r=1)
so
F1/F2 = A1/A2
100/10000 = pi*r^2/Pi*1
r1= 0.1 (ans.)