Answer:
0.4 s
Step-by-step explanation:
The time that the ball is in the air can be found with the next formula:

where
is the initial velocity of the ball, in this case:

β is the angle: β = 29.0°
And g is the acceleration of gravity:

Replacing all the values to find t, we have:

Thus, the ball is 0.4s in the air.