Here's our equation.

We want to find out when it returns to ground level (h = 0)
To find this out, we can plug in 0 and solve for t.


So the ball will return to the ground at the positive value of

seconds.
What about the vertex? Simple! Since all parabolas are symmetrical, we can just take the average between our two answers from above to find t at the vertex and then plug it in to find h!

Answer:
StartFraction 1.55 over 1 EndFraction = StartFraction x over 3.5 EndFraction
Step-by-step explanation:

<span>As the age of the U-235 sample is 2.631 billion years, and the half-life of U-235 is 713 million years, the sample has undergone 2.361 X 1,000,000,000 / 713 X 1,000,000 = 3.69 half lives. In each half-life the sample reduces to half its original weight according to the radioactive Half-Life Formula:
ln (Nt /N0) = -kt, where N0 = mass of the original weight of radioactive material, Nt = mass of radioactive material at time t, k = decay constant and t = time interval . We have to put Nt/N0 = 1/2 for time interval = half-life.</span>
I’m not so sure i’m sorry