Answer:
t = 4.28 s
Explanation:
The horizontal speed of a marble = 7 m/s
The horizontal displacement covered by the marble = 30 m
We need to find the time for which the marble is in air. Let the time is t. Using the formula for speed to find it as follows :
[tex]s=\dfrac{d}{t}\\\\t=\dfrac{d}{s}\\\\t=\dfrac{30\ m}{7\ m/s}\\\\=4.28\ s[/tex]
So, it will in the air for 4.28 s.