Center Of Mass

A ball of mass \(200 \mathrm{~g}\) rests on a vertical post of height \(20 \mathrm{~m}\). A bullet of mass \(10 \mathrm{~g}\), travelling in horizontal direction, hits the centre of the ball. After collision both travels independently. The ball hits the ground at a distance \(30 \mathrm{~m}\) and the bullet at a distance of \(120 \mathrm{~m}\) from the foot of the post. The value of initial velocity of the bullet will be (if \(g=10 \mathrm{~m} / \mathrm{s}^{2}\)) :