SOLUTION: A ball is thrown downward from a building window. It's position at time t in seconds is s = 16t^2 + 32t where s is in feet. How long (nearest tenth) will it take the ball to fall

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Question 507332: A ball is thrown downward from a building window. It's position at time t in seconds is s = 16t^2 + 32t where s is in feet. How long (nearest tenth) will it take the ball to fall 233 feet?
A. 3.8 sec
B. 2.7 sec
C. 8.41 sec
D. 2.9 sec
Answer by MathLover1(20855) About Me  (Show Source):
You can put this solution on YOUR website!
s+=+16t%5E2+%2B+32t where s is in feet
How long (nearest tenth) will it take the ball to fall 233ft
start with:

s+=+16t%5E2+%2B+32t ...plug in s

233ft+=+16t%5E2+%2B+32t ..........solve for t

+16t%5E2+%2B+32t-233+=0

t+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+

t+=+%28-32+%2B-+sqrt%28+32%5E2-4%2A16%2A%28233%29+%29%29%2F%282%2A16%29+

t+=+%28-32+%2B-+sqrt%28+1024%2B14912+%29%29%2F32+

t+=+%28-32+%2B-+sqrt%28+15936%29%29%2F32+

t+=+%28-32+%2B-+126.24%29%2F32+
solution (you need only positive solution)
t+=+%28-32+%2B126.24%29%2F32+
t+=+%2894.2%29%2F32+
t+=+2.9+
so, your answer is:
D. 2.9sec