(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The driver of a car traveling at 71 ft/sec suddenly applies the brakes. The position of the car is s = 71t - 20t^{2}, t seconds after the driver applies the brakes. After how many seconds does the car come to a stop? Round your answer to the nearest tenth.

2. Relevant equations

3. The attempt at a solution

s=71t-20t^{2}

0=71t-20t^{2}

0=71-20t

t=71/20

t=3.55 =3.6

However the correct answer is1.8, which is half my answer, but I do not understand why you would divide by 2? Or where I went wrong?

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# Why is the answer half of my answer?

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