Answer:
- Time = approximately mid 2012
- Oil import rate = 3600 barrels
Step-by-step explanation:
<h3><em>Unclear part of the question</em></h3>
- I(t) = −35t² + 800t − 1,000 thousand barrels per day (9 ≤ t ≤ 13)
- According to the model, approximately when were oil imports to the country greatest? t = ?
<h3>Solution</h3>
Given the quadratic function
- <em>The vertex of a quadratic function is found by a formula: x = -b/2a</em>
<u>As per given function:</u>
<u>Then</u>
- t = - 800/2*(-35) = 11.43 which is within given range of 9 ≤ t ≤ 13
This time is approximately mid 2012.
<u>Considering this in the function, to get oil import rate for the same time:</u>
- l(11.43) = -35*(11.43)² + 800*11.43 - 1000 = 3571.4285
<u>Rounded to two significant figures, the greatest oil import rate was</u>:
First we need to know the total area. Since this is a rectangle we need two adjacent sides and we can find these from vertex pairing:
Matching y: (3,9) --> (5,9) = 2 ft
Matching x: (3,9) --> (3,3) = 6 ft
Area = l*w = 2*6 = 12 square ft
# of bags = 12sqft/(5sqft/bag) = 2.4 bags.
Cost = $5.00 * 2.4 = $12 (notice that it cost $1 to cover 1sqft so we could have skipped a step here.)
NOTE: In the real world she probably can't buy just 0.4 of a bag and would actually have to buy three full bags for $15.
The equation formula is y - y1 = m(x-x1)
Using the first point for x1, y1:
Y +13 = m(x-15)
M is the slope which is the change in y over the change in x:
M = -11–13 / 16-15 = 2/1 = 2
The equation becomes y +13 =2(x+15)
The answer is:
He incorrectly wrote the slope in his equation. He should have written y+13=2(x−15).
