Answer:
c
Step-by-step explanation:
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Find 2% of 7 billion.
7,000,000,000 x .02 = 140,000,000
About 140 million people have red hair.
Answer:
Rounded to the nearest integer, the test had 18 problems in all.
Step-by-step explanation:
Given that a student missed 10 problems on an English test and received a grade of 44%, if all the problems were of equal value, to determine how many problems were on the test the following calculation must be performed:
100 - 44 = 56
56 = 10
100 = X
100 x 10/56 = X
1,000 / 56 = X
17.85 = X
Thus, rounded to the nearest integer, the test had 18 problems in all.
The given matrix equation is,
![1.5\left[\begin{array}{cc}x&6\\8&4\end{array}\right] +y\left[\begin{array}{cc}1&4\\3&2\end{array}\right] =\left[\begin{array}{cc}z&z\\6z&2\end{array}\right]](https://tex.z-dn.net/?f=%201.5%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7Dx%266%5C%5C8%264%5Cend%7Barray%7D%5Cright%5D%20%2By%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D1%264%5C%5C3%262%5Cend%7Barray%7D%5Cright%5D%20%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7Dz%26z%5C%5C6z%262%5Cend%7Barray%7D%5Cright%5D%20%20)
.
Multiplying the matrices with the scalars, the given equation becomes,
![\left[\begin{array}{cc}1.5x&9\\12&6\end{array}\right] +\left[\begin{array}{cc}y&4y\\3y&2y\end{array}\right] =\left[\begin{array}{cc}z&z\\6z&2\end{array}\right] \\](https://tex.z-dn.net/?f=%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D1.5x%269%5C%5C12%266%5Cend%7Barray%7D%5Cright%5D%20%2B%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7Dy%264y%5C%5C3y%262y%5Cend%7Barray%7D%5Cright%5D%20%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7Dz%26z%5C%5C6z%262%5Cend%7Barray%7D%5Cright%5D%20%20%5C%5C%20%20)
Adding the matrices,
![\left[\begin{array}{cc}1.5x+y&9+4y\\12+3y&6+2y\end{array}\right] =\left[\begin{array}{cc}z&z\\6z&2\end{array}\right] \\](https://tex.z-dn.net/?f=%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7D1.5x%2By%269%2B4y%5C%5C12%2B3y%266%2B2y%5Cend%7Barray%7D%5Cright%5D%20%20%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7Dz%26z%5C%5C6z%262%5Cend%7Barray%7D%5Cright%5D%20%20%5C%5C%20)
Matrix equality gives,
Solving the equations together,
We can see that the equations are not consistent.
There is no solution.
Answer:
Step-by-step explanation:
For mixture problems, it is convenient to define a variable to represent the amount of the greatest contributor. Let x represent the amount of 22% solution in the mix. Then 4.8-x is the amount of 10% solution.
The amount of alcohol in the mix is ...
0.22x +0.10(4.8-x) = 0.12(4.8)
Eliminating parentheses, we have ...
0.22x -0.10x +0.10(4.8) = 0.12(4.8)
Subtracting (0.10)(4.8) and combining x-terms gives ...
0.12x = 0.02(4.8)
x = (0.02/0.12)(4.8) = 0.8 . . . . . divide by the x-coefficient
The scientist needs 0.8 L of 22% solution and 4.0 L of 10% solution.
