To determine when the water balloon will hit the ground, we can use the formula provided:
\[ y = -16t^2 + 30t + 8 \]
Here, \( y \) represents the height of the balloon (in feet), and \( t \) represents time (in seconds). The balloon will hit the ground when \( y = 0 \). Therefore, we need to solve the equation:
\[ -16t^2 + 30t + 8 = 0 \]
To solve this quadratic equation, we can use the quadratic formula, which is given by:
\[ t = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]
In this case, \( a = -16 \), \( b = 30 \), and \( c = 8 \). Plugging these values into the formula gives:
- Calculate \( b^2 - 4ac \):
\[ b^2 - 4ac = 30^2 - 4(-16)(8) \]
\[ = 900 + 512 \]
\[ = 1412 \]
- Now use the quadratic formula:
\[ t = \frac{-30 \pm \sqrt{1412}}{2(-16)} \]
First, calculate \( \sqrt{1412} \):
\[ \sqrt{1412} \approx 37.5 \]
Now substitute that back in:
\[ t = \frac{-30 \pm 37.5}{-32} \]
This gives us two potential solutions for \( t \):
\[ t = \frac{-30 + 37.5}{-32} \quad \text{and} \quad t = \frac{-30 - 37.5}{-32} \]
Calculating each:
- For \( -30 + 37.5 \):
\[ t = \frac{7.5}{-32} \approx -0.234375 \quad (\text{not valid as time cannot be negative}) \]
- For \( -30 - 37.5 \):
\[ t = \frac{-67.5}{-32} \approx 2.109375 \]
Rounding this to the nearest tenth, we find:
\[ \boxed{2.1} \text{ seconds} \]
Thus, the water balloon will hit the ground approximately 2.1 seconds after being thrown.