Answer:
In 2.748 sec the mailbag reached the ground
Step-by-step explanation:
We have given height from the ground

At t =2.25 sec helicopter releases a small mailbag so at t = 2.25 sec height from the ground

When the mail box is drooped its initial velocity would zero so u = 0 m/sec
Acceleration due to gravity

According to third law of motion



t = 2.748 sec