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neonofarm [45]
3 years ago
11

the ratio of boys to girls in a classroom is 7:5 4 boys are added to the class the ratio is now 1:1 find the total number of gir

ls in the class
Mathematics
1 answer:
OLEGan [10]3 years ago
7 0

Answer:

14

Step-by-step explanation:

7/5. = x/ x- 4 (the ratio to each other is the same)

cross multiply

7x-28 = 5x

simplified: -2x = -28

divide x and -28 by -2

x= 14

x= # of girls

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Plug the values of x into each equation

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Answer:

A), B) and D) are true

Step-by-step explanation:

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D) Let A be an orthogonal matrix in \mathbb{R}^n. Then the columns of A form an orthonormal set. We have that A^{-1}=A^t. To see this, note than the component b_{ij} of the product A^t A is the dot product of the i-th row of A^t and the jth row of A. But the i-th row of A^t is equal to the i-th column of A. If i≠j, this product is equal to 0 (orthogonality) and if i=j this product is equal to 1 (the columns are unit vectors), then A^t A=I    

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5 0
3 years ago
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Citrus2011 [14]

Answer:

6.48%

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