A proportion looks like this:
It means that the quantity a,b,c and d are in the same proportion: the ratio between a and b is the same ratio between c and d.
They are particularly useful in situation when you have an example given, and you want to extrapolate the relationship for another couple.
For example, you can think of the following problem: "Five apples cost 2 dollars. How much will 8 apples cost?"
You can build the proportion
And then solve it for x:
to do it in mental math: you can ignore the zeroes in 400 for now.
4*14 = 4*10 + 4*4 = 40 + 16 = 56
now add the zeroes back on: 5600m
Answer: y = 6 mi. .
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Explanation:
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Area of a triangle = (½) * (base) * (height) ;
or, A = (½) * b * h ; or, A = b*h / 2 ;
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Given: A = 24.3 mi ² ;
b = 8.1 mi
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Find the height, "h" ; (in units of "miles", or , "mi" ).
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Plug in the known values into the formula:
24.3 mi ² = (½) * (8.1 mi) *(h) ;
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Solve for "h" (height) ;
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(½) * (8.1 mi) = 4.05 mi ;
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Rewrite:
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24.3 mi² = (4.05 mi) *(h) ; Solve for "h" ;
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Divide each side of the equation by "(4.05 mi)" ; to isolate "h" on one side of the equation ; and to solve for "h" ;
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24.3 mi² / 4.05 mi = (4.05 mi) *(h) / 4.05 mi ;
→ 6 mi = h ; ↔ h = 6 mi.
→ h = y = 6 mi.
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132.40 should be the answer
