Only selections B and D give a maximum height of 13 at t=3. However, both of those functions have the height be -5 at t=0, meaning the ball was served from 5 ft below ground. This does not seem like an appropriate model.
We suspect ...
• the "correct" answers are probably B and D
• whoever wrote the problem wasn't paying attention.
X=8.
Following the similarity statement, we know that AC is to DF as BC is to EF. The ratio would be:
24/(x-2) = 20/5
Cross multiply:
24*5 = 20(x-2)
Use the distributive property:
120 = 20x - 40
Add 40 to both sides:
120+40 = 20x - 40 + 40
160 = 20x
Divide both sides by 20:
160/20 = 20x/20
8 = x
So, how much acid is there in 6 gallons? well is 20% acid or (20/100), so the amount of acid in it just (20/100) * 6 or 1.2, the rest is say water.
now, if we want a 90% solution, and say we add "y" gallons, how much acid is in it? well (90/100) * y, or 0.9y.
now let's add "x" gallons of pure acid, now, pure acid is just pure acid, so is 100% acid, how much acid is there in it? (100/100) * x, or 1x or just x.
we know whatever "x" and "y" amounts are, they -> x + 6 = y
and we also know that x + 1.2 = 0.9y