Let us bear in mind the equivalent value of these coins:
One dime = $0.10
One quarter = $0.25
Let x = number of dimes
y<span> = number of quarters</span>
Since the boy has 70 coins in total, we can say that:
<span>x + y = </span><span>70 </span>(can be written as x = 70 – y)
Since the boy has a total of $12.40, we can say that:
0.10x + 0.25y = 12.40
To solve this problem, we need to solve this system of equation. We have to substitute the value of x as written in the first equation (x = 70 –y)
0.10(70 – y) + 0.25y = 12.40
7 – 0.10y + 0.25y = 12.40
0.15y = 5.40
y = 36
X = 70 – 36
X = 34
Therefore,<span> the boys </span>has<span> 34 dimes and 36 quarters. To check our answer, we just have to check if his money would total $12.40.</span>
34 dimes = $3.40
36 dimes = $9.00
<span>Total </span><span>$12.40</span>
The quadratic regression equation for the stream of water is
{parabola}
Given that the water stream produced by fountain is parabola
Vertex of parabola is (6,5) , parbola is facing downward,axis of symmetry of parabola is x=6 and parabola passes through (0,0)
according to symmetry the third point on the parabola is (12,0)
General equation for a parabola⇒ Y=-4a
⇒(y-5)=-4a
{ as the Vertex of parabola is (6,5) }
⇒(y-5)=-4a(
)
subtituting (0,0) in the equation to get the value of a
⇒-5=-4a(36)
⇒ a=
equation of parabola⇒(y-5)=-4(
)
Therefore,The quadratic regression equation for the stream of water is 
Learn more about parabola here:
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The volume of the given trapezoidal prism is 312 cubic units.
Step-by-step explanation:
Step 1:
To find the volume of a trapezoidal prism, we multiply the area of the trapezoidal surface with the height of the prism.
The area of a trapezoidal surface, 
a and b are the lengths of the upper and lower bases and h is the height of the trapezoid.
For the given trapezoid, a is 5 units long and b is 8 units long while height, h is 4 units.
The area of the trapezoidal surface, 
So the area of the trapezoidal surface is 26 square units.
Step 2:
To determine the volume of the prism, we multiply the area of the trapezoidal surface with the height of the prism.
The area is 26 square units and the height of the prism is 12 units.
The volume of the prism, 
The volume of the given trapezoidal prism is 312 cubic units.