Answer:
1 1/8 ga / 13.5 mi = .0833 ga / mi
1 / .0833 ga/mi = 12 mi / ga
or .0833 ga/mi * 13.5 mi = 1.25 ga
Formula
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d = r * t
Givens
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d = 2 3/4
t = 1 hour 15 minutes
r = ????
Calculations
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You need to convert the 15 minutes to hours.
1 hour = 60 minutes
x hour = 15 minutes
1/60 = x/15
x = 15/60
x = 0.25 hours
so the time = 1 hours + 0.25 hours
t = 1.25 hours
Now you need to do something with the distance.
3/4 mile = 0.75 of a mile
So the distance = 2 + 0.75 = 2.75 miles
Now you are ready for the answer.
d = r * t you are looking for r
2.75 = r * 1.25
r = 2.75/1.25
r = 2.2 miles / hour
Note you could do this with fractions.
2 3/4 = 11/4
1 1/4 = 5/4
r = 11/4 // 5/4 =11/5 = 2 1/5 which is the same thing as 2.2. If your calculator can handle fractions (those kind of calculators cost about 10 dollars in Canada. It should be 8 in the US) that might be the way to do this problem.
3, 5, 7
wanna know why, or do you not care?
I assume that the parabola in this particular problem is one whose axis of symmetry is parallel to the y axis. The formula we're going to use in this case is (x-h)2=4p(y-k). We know variables h and k from the vertex (1,20) but p is not given. However, we can solve for p by substituting values x and y in the formula with the y-intercept:
(0-1)^2=4p(16-20)
Solving for p, p=-1/16.
Going back to the formula, we can finally solve for the x-intercepts. Simply fill in variables p, h and k then set y to zero:
(x-1)^2=4(-1/16)(0-20)
(x-1)^2=5
x-1=(+-)sqrt(5)
x=(+-)sqrt(5)+1
Here, we have two values of x
x=sqrt(5)+1 and
x=-sqrt(5)+1
thus, the answers are: (sqrt(5)+1,0) and (-sqrt(5)+1,0).
Use order of operations, or PEMDAS which stands for Parenthesis, Exponent, Division, Addition, and Subtraction.
Do those operations in that order. Can you try?
What will be the first thing you do here, according to PEMDAS?
