900. It estimates bc one is like 288 and one is like 624 or sum.
Well, Doing 8,600 x .0395, you get 339.7, then if you do that x 25, that's too low if you add 8600 to it, 36 years if you do 339.7 x 25, then add 8600 its extremely close to 21000. And since you put approximately, since this will round up, the best answer choice is definitely B
Hope this helps. Have a great day!
Answer:
Step-by-step explanation:
Given that a rock is thrown vertically upward from the surface of an airless planet. It reaches a height of 
where t is expressed in seconds
The rock goes upto a height where the velocity becomes 0 and then it starts falling down by gravity
Velocity at time t = s'(t) = 
This becomes 0 when t =15 seconds
Hence at 15th second the rock starts falling and upto
s(15) =
metres high it goes
The time taken to reach highest point is = 15 seconds.
Follow the steps in order how to know how to divide