Answer: $20.59
Step-by-step explanation:
0.13 * 6 = 0.78
25 - 0.78 = 24.22
85% * 24.22 = 20.59
Answer:
You need to have some idea where you want to start if you're going to derive equations for these. You can start with a definition based on focus and directrix, or you can start with a definition based on the geometry of planes and cones. (The second focus is replaced by a directrix in the parabola.) In general, these "conics" represent the intersection between a plane and a cone. Perpendicular to the axis of symmetry, you have a circle. At an angle to the axis of symmetry, but less than parallel to the side of the cone, you have an ellipse. Parallel to the side of the cone, you have a parabola. At an angle between the side of the cone and the axis of the cone, you have a hyperbola. (See source link.)
You can also start with the general form of the quadratic equation.
.. ±((x-h)/a)^2 ± ((y-k)/b)^2 = 1
By selecting signs and values of "a" and "b", you can get any of the equations. (For the parabola, you probably need to take the limit as both k and b approach infinity.)
We have two unknowns and two equations so we can solve this question.
The two unknowns are C (speed of current) and B (speed of boat)
Our boat traveled 20 miles in 55 hours going upstream which means it traveled .36 miles in 1 hour; in other words .36mph . Our boat traveled 50 miles in 55 hours going downstream; in other words .909mph .
We can assume that because the boat managed to cover distance in the direction it was headed upstream it must have been going faster than the current so it moved at the speed of the boat minus the speed of the current and when it was going downstream it moved at the speed of the boat plus the speed of the current.
This gives us;
.36mph = B - C
.909mph= B + C
We solve for this system of equations and it simplifies to 1.27mph=2B
and B= .636mph
Plug this into one of the equations and we get that C= .2727mph
This means that the boat moved at .363mph and the current moved at .2727mph.