acceleration of rocket is
[tex]a = 44.1 m/s^2[/tex]
time taken by rocket
[tex]t = 7 s[/tex]
so the distance covered by rocket will be
[tex]d = \frac{1}{2}at^2[/tex]
[tex]d = \frac{1}{2}*44.1 * 7^2[/tex]
[tex]d = 1080.45 m[/tex]
speed of the rocket
[tex]v = v_i + at[/tex]
[tex]v = 0 + 44.1 * 7 = 308.7 m/s[/tex]
now the maximum height it will reach from this is given by
[tex]v_f^2 - v_i^2 = 2 a d[/tex]
[tex]0 - 308.7^2 = - 2* 9.8 * d[/tex]
[tex]d = 4862 m[/tex]
so the total height of rocket will be
[tex]H = 1080.45 + 4862 = 5942.5 m[/tex]