The answer is = -3, hope this helps!
Answer:
13.5 in, or 34.3 cm.
Step-by-step explanation:
First, use the formula volume = pi * r^2 * height- you have the volume, so just solve the equation 411pi = pi * 9 * r^2 for r, and you get that r = 6.75. Since diameter is equal to 2r, multiply 6.75 by 2 to get your answer of 13.5 inches. The questions asks for the diameter in centimeters though, which makes it 34.3 cm.
Hopefully this helps- let me know if you have any questions!
The equation gives the height of the ball. That is, h is the height of the ball. t is the time. Since we are looking for the time at which the height is 8 (h=8), we need to set the equation equal to 8 and solve for t. We do this as follows:




This is a quadratic equation and as it is set equal to 0 we can solve it using the quadratic formula. That formula is:

You might recall seeing this as "x=..." but since our equation is in terms of t we use "t-=..."
In order to use the formula we need to identify a, b and c.
a = the coefficient (number in front of)

= 16.
b = the coefficient of t = -60
c = the constant (the number that is by itself) = 7
Substituting these into the quadratic formula gives us:



As we have "plus minus" (this is usually written in symbols with a plus sign over a minus sign) we split the equation in two and obtain:

and

So the height is 8 feet at t = 3.63 and t=.12
It should make sense that there are two times. The ball goes up, reaches it's highest height and then comes back down. As such the height will be 8 at some point on the way up and also at some point on the way down.
1620/ 5 is =324
To check just multiply
5 * 324