Sean needs to figure out how much paint he needs in order to cover all of the sides of his ramp. what is the surface area of the
ramp?
a) 102 cm2
b) 210 cm2
c) 258 cm2
d) 432 cm2
a) 102 cm2
b) 210 cm2
c) 258 cm2
d) 432 cm2
2 answers:
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<h3>Answer: 16 ft by 25 ft</h3>
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Explanation:
Refer to the diagram below.
The outer dimensions 24 ft and 33 ft shrink down to 24-2x ft and 33-2x ft respectively. This subtraction of 2x is due to subtracting two copies of x per side.
The carpet has area of (24-2x)(33-2x)
Cynthia can afford to buy 400 sq ft of carpet
So we set 400 equal to that previous expression and solve for x
(24-2x)(33-2x) = 400
24(33-2x) - 2x(33-2x) = 400
792-48x - 66x + 4x^2 = 400
4x^2 - 114x + 792 = 400
4x^2 - 114x + 792-400 = 0
4x^2 - 114x + 392 = 0
From here, use the quadratic formula to isolate x.
Plug in a = 4, b = -114, c = 392
The two possible solutions are x = 24.5 and x = 4
But if x = 24.5, then 24 - 2x = 24 - 2*24.5 = -25 which isn't possible. We cannot have a negative width or negative length for the carpet.
Luckily x = 4 does work since
24 - 2x = 24 - 2*4 = 16
33 - 2x = 33 - 2*4 = 25
Both results are positive.
Therefore, the carpet has dimensions of <u>16 ft by 25 ft</u>
Check: 16*25 = 400, so the answer is confirmed