Will a conversion kick clear the crossbar

In a rugby conversion the ball must pass over a crossbar \(3\) m above the ground. A ball is kicked from the ground straight towards the posts, and its height \(h\) m when it has travelled \(x\) m horizontally is modelled by \(h=\dfrac{x(40-x)}{100}\).

1. By completing the square, find the greatest height of the ball and the horizontal distance at which it occurs.[2]
2. The posts are \(d\) m from the kicker. Find the values of \(d\) for which the ball is exactly at crossbar height when it reaches the posts, and hence the range of values of \(d\) for which the ball passes over the crossbar.[3]
3. State two assumptions of the model. A player kicks from \(25\) m. Use your answer to (b) and the context to judge whether the ball is likely to clear the crossbar in practice.[3]