Step-by-step explanation:
Given that,
Initial speed of the toy rocket, u = 45 m/s
Let t is the time taken by the rocket to reach it's highest point. At the highest point the final speed of the rocket is 0. Using equation of kinematics to find the value of t as :


Here, a = -g


t = 4.59 seconds
So, the rocket will take 4.59 seconds to reach its highest point. Hence, this is the required solution.