We know that
the equation of the parabola is of the form
y=ax²+bx+c
in this problem
y=1/4x²−x+3
where
a=1/4
b=-1
c=3
the coordinates of the focus are
(-b/2a,(1-D)/4a)
where D is the discriminant b²-4ac
D=(-1)²-4*(1/4)*3-----> D=1-3---> D=-2
therefore
x coordinate of the focus
-b/2a----> 1/[2*(-1/4)]----> 2
y coordinate of the focus
(1-D)/4a------> (1+2)/(4/4)---> 3
the coordinates of the focus are (2,3)
For this, we can set up a proportion.
Their aim was 15000, so if they raised 100% of their goal, they wouldve raised exactly 15000.
They raised 557%, so how much did they make?
Proportion:
$15000 100%
$x 557%
Our expression would be x=$15000*557% divided by 100%, which would be $83550, so... a lot of money.
(we did an “x” formation with the proportion, ie “connected” x with 100, and “connected” 15k and 557. The number connecting to x is what we divide the equation by, and the other two are multiplied and then divided by the first number connecting to x. Otherwise we couldve calculated 557% of 15000 and gotten the same result. Whichever way is easier for you :) )
Selection C is appropriate.
_____
A. The population is constant at 8.
B. The population is constant at 24.
C. Matches the problem description.
D. The initial population is 24 and after 1 hour is 72.
11.6 rounded to the nearest whole is 12 and 4.1 rounded to the nearest whole is 4 (rule is if the decimal [or number in general] is 4 or lower, the whole stays the same and if the number is 5 or higher, the whole goes up by one). 12+4=16
If it is 76 feet LOWER than 73 above sea level, then you must do
73-76= -3
So Mudville is 3 feet BELOW sea level.