Short Answer: Current speed = 3 miles per hour.
Givens
Downstream
d = 4.48 miles
t = 0.32 hours.
c = ??
r_boat = ??
Upstream
d = 4.48 miles
t = 0.56 miles
c = ??
r_boat =??
Equations.
Since the distances are the same, you can equate the distances and come back to them later.
d = r*t
(r - c) * 0.56 = (r + c) * 0.32 This will give you r in terms of c. Notice the minus sign on the left. It's there because the current is going against you, slowing you down.
Remove brackets
0.56r - 0.56c = 0.32r + 0.32c Add 0.56c to both sides.
0.56r = 0.32r + 0.32c + 0.56c
0.56r = 0.32r + 0.88c Subtract 0.32r from both sides.
0.56r - 0.32r = 0.88c
0.24r = 88c Divide by 0.24
r = 0.88/0.24 c
r = 3 2/3 c
Now we have enough information to solve for c
4.48/(r + c) = 0.32
4.48 = 0.32 * (r + c) Substitute r = 3 2/3c into this equation.
4.48 = 0.32 * (3 2/3c + c) Add c and 3 2/3c together.
4.48 = 0.32 * (4 2/3c) Change 4 2/3 to 14/3
4.48 = 0.32 * 14/3 c
4.48 = (4.48 / 3 ) * c
4.48 = 1.493333333 c Divide 4.48 by 1.493333333
c = 4.48 / 1.4933333
c = 3 mph <<<<<<<<<<<<<<Answer
Answer: Choice C) $15
There are two ways to get this answer
Method 1 is to subtract 700-550 = 150 and then take 10% of that to get 15
We take 10% since this is the percentage Ricardo has to pay (the employer takes care of the other 90%)
Method 2 is to take 10% of 700 and 550 to get 70 and 55 respectively. Then subtract to get 70-55 = 15
Either way the answer is 15
solve for "w", to find the wind's speed rate,
so hmmm what's the plane's rate? well 420 - w = r :)
For a general quadratic equation, we want to find the equations for the vertex (h, k).
The values of the vertex are:
- h = -b/(2*a)
- k = f(h) = b^2/(4a) - b^2/(2a) + c
We start with the general quadratic equation:
f(x) = a*x^2 + b*x + c
To find the x-value of the vertex (h in this case) we need to find the zero of the first derivate of f(x) (because the vertex is a minimum/maximum of the function).
We have:
f'(x) = 2*a*x + b
We solve:
f'(h) = 0 = 2*a*h + b
-b/(2*a) = h
So we just found the value of h.
To find the value of k, the y-value of the vertex, we need to evaluate the function in the x-value of the vertex, we will get:
k = f(h) = a*( -b/(2*a))^2 + b*( -b/(2*a)) + c
k = b^2/(4a) - b^2/(2a) + c
Then, concluding, we have:
- h = -b/(2*a)
- k = f(h) = b^2/(4a) - b^2/(2a) + c
If you want to learn more, you can read:
brainly.com/question/8552341