Need major help with Precalc?

Need major help with Precalc?In sixteen states and the District of Columbia, the legal blood-alcohol level is 0.08. Use the formula A(x) = -0.0082x2 + 0.06x to compute blood-alcohol levels as a function of x (the time in hours). When is the first time that a person can be arrested for drunken driving after drinking 5 ounces of 80-proof whiskey in those states? (Hint: To find an answer through approximation, calculate the blood-alcohol level for every 0.2 hours beginning at x = 0.2.)

1.8 hours
2.2 hours
1.6 hours
3.0 hours

I think it's either 1.6 or 1.8

Answer by Glenn Curth
The way I see it, it is quite easy to calculate. You are looking for the time in hours (x) it takes to reach the a certain level of blood alcohol (A(x))= 0.08. So you just put that in the formula and solve for x:

0.08 = - 0.0082x² + 0.06x

I will not preform the calculation in detail, since it requires you to estimate it by using intervals of 0.2 hours I suppose you are not yet able to do it on your own.

The exact solution would be after 1.7536 hours, so rounding that up to the next interval of 0.2 your correct answer would be 1.8 hours.

If you want to know how to do the calculation then send me an email!

Cheers!

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