Answer:
Step-by-step explanation:
-9x^3(x^2 - 4x - 21) =
-9x(x - 7)(x + 3) <===
<h3>
Answer: angle X = 70.5 degrees</h3>
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Work Shown:
Law of Cosines
c^2 = a^2 + b^2 - 2ab*cos(C)
22^2 = 20^2 + 18^2 - 2*20*18*cos(X)
484 = 724 - 720*cos(X)
484 + 720*cos(X) = 724
720*cos(X) = 724 - 484
720*cos(X) = 240
cos(X) = 240/720
cos(X) = 1/3
X = arccos(1/3)
X = 70.528779
X = 70.5
Make sure your calculator is in degree mode.
answer
$962.50
set up equation
first, we want to find out how many gallons of gas she'll save a year
x1 = gallons for old car
x2 = gallons for new car
gallons saved = x1 - x2 since she uses more gallons with the old car with a lower miles per gallon
then, find how much she saves on gas by multiply the price per gallon (3.85) by gallons saved
price saved = gallons saved * price
price saved = (x1 - x2) * 3.85
gallons with old car
to find the number of gallons, we divide the number of miles (15000) by miles per gallon (24 for the old car)
x1 = 15000 / 24
x1 = 625
gallons with new car
use the same process as with the old car, but with 40 miles per gallon instead
x2 = 15000 / 40
x2 = 375
plug in values
price saved = (x1 - x2) * 3.85
price saved = (625 - 375) * 3.85
price saved = 250 * 3.85
price saved = $962.50
<span>It can be assumed that the sample mean would would be approximately normal by the mean distribution theorem. The mean distribution theorem states that a large enough sample size will have a distribution and mean approximately the same as the population mean. A sample of 250, half the size of 500, is of sufficient size to assume the distribution mean will be approximately normal like the population mean.</span>
