SOLUTION: An arrow shot into the air is 160t-4.9t^2 meters above the ground t seconds after its released. During what period(s) of time is the arrow below 117.6 meters? Round your answer to

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Question 595766: An arrow shot into the air is 160t-4.9t^2 meters above the ground t seconds after its released. During what period(s) of time is the arrow below 117.6 meters? Round your answer to the nearest .01 second.
A) t<0.75 and t>31.90 seconds
B) t<8.65 and t> 24 seconds
C)0.75 D) 8.65
Answer by lwsshak3(11628) About Me  (Show Source):
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An arrow shot into the air is 160t-4.9t^2 meters above the ground t seconds after its released. During what period(s) of time is the arrow below 117.6 meters? Round your answer to the nearest .01 second.
**
f(t)=160t-4.9t^2
117.6=160t-4.9t^2
4.9t^2-160t+117.6=0
use following quadratic formula to solve for t
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
a=4.9, b=160, c=117.6
t=.75 and 31.90 seconds
answer A