Answer:
I believe that the answer is 26
Step-by-step explanation:
The ratio of girls to boys is 13 to 8 so there are 13 girls for every 8 boys so if there are 16 boys (8X2) then there are 26 girls (13X2)
Let a₁ , a₂ , a₃ , a₄ ,... .be a given sequence.
The common ratio of this sequence is the following:
a₂/a₁ = a₃/a₂ = a₄/a₃ = r
Example: 5, 25, 125, 625, ...The common ration is:
25/5 = 125/25 = 625/125 = 5. So r=5 is the common ratio
surface area (S) of a right rectangular solid is:
S = 2*L*W + 2*L*H + 2*W*H (equation 1)
where:
L = length
W = width
H = height
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you have:
L = 7
W = a
H = 4
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formula becomes:
S = 2*7*a + 2*7*4 + 2*a*4
simplify:
S = 14*a + 56 + 8*a
combine like terms:
S = 22*a + 56
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answer is:
S = 22*a + 56 (equation 2)
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to prove, substitute any value for a in equation 2:
let a = 15
S = 22*a + 56 (equation 2)
S = 22*15 + 56
S = 330 + 56
S = 386
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since a = 15, then W = 15 because W = a
go back to equation 1 and substitute 15 for W:
S = 2*L*W + 2*L*H + 2*W*H (equation 1)
where:
L = length
W = width
H = height
-----
you have:
L = 7
W = 15
H = 4
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equation 1 becomes:
S = 2*7*15 + 2*7*4 + 2*15*4
perform indicated operations:
S = 210 + 56 + 120
S = 386
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surface area is the same using both equations so:
equations are good.
formula for surface area of right rectangle in terms of a is:
S = 22*a + 56
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105 - 75 = 30 That should do it.
