Answer:
Step-by-step explanation:
Given
maximum height reached
![h=72\ m](https://img.qammunity.org/2021/formulas/physics/college/9nlr46nhp29wl2wg3s3mqfrnp0idz7gqaa.png)
suppose Projectile is launched vertically with initial velocity u
applying equation of motion
![v^2-u^2=2 as](https://img.qammunity.org/2021/formulas/physics/college/dy87dk2gx8nzcp5jvhem69c3ewm6bt1ljf.png)
where v=final velocity
u=initial velocity
a=acceleration
s=displacement
Here final velocity is zero so
![s=frac{u^2}{2g}](https://img.qammunity.org/2021/formulas/physics/college/uspxgil1vdxslkw1vhvvbfdb2rvo021x2p.png)
for twice initial velocity
![s'=((2u)^2)/(2g)](https://img.qammunity.org/2021/formulas/physics/college/v92kvd4v4q00tiduraqrhjmedg25ry8o07.png)
![s'=4* (u^2)/(2g)](https://img.qammunity.org/2021/formulas/physics/college/i70mcjakdojvts4sat5rtlg38fc87y5pft.png)
![s'=4* 72](https://img.qammunity.org/2021/formulas/physics/college/2e10r69u16hpj5f1a045izmq952j1sjch7.png)
![s'=288\ m](https://img.qammunity.org/2021/formulas/physics/college/53kvqonnulxzl8w6qsn2qk9e0xmflzo7q5.png)