A ball is thrown from level ground at 20 m/s, at 45°.

Step 1. Time to the wall. $u_x = 20\ \text{m/s}\cos 45^\circ = 14.14\ \text{m/s}$, so $t = \dfrac{30\ \text{m}}{14.14\ \text{m/s}} = 2.12\ \text{s}$.

Step 2. Height then. $u_y = 14.14\ \text{m/s}$, so $y = 14.14\ \text{m/s} \times 2.12\ \text{s} - 4.9\ \text{m/s}^2 \times (2.12\ \text{s})^2 = 30.0\ \text{m} - 22.05\ \text{m} = 7.95\ \text{m}$.

Step 3. Compare. $7.95\ \text{m}$ is more than $6.0\ \text{m}$.