MATHEMATICS MIDDLE SCHOOL

The librarian was checking the thicknesses of several books and found that the average thickness of a book was 1.8 centimeters. She found this by averaging the thicknesses of five different books. Four of the thicknesses were 1.4 cm, 1.9 cm, 2.1 cm, and 2.4 cm. What was the thickness of the fifth book that she measured?

Answers

Answer 1
Answer:

Answer:

1.2 cm

Step-by-step explanation:

1.8 * 5 = 9

9 - (1.4 + 1.9 + 2.1 + 2.4) = 1.2

1.2 + 1.4 + 1.9 + 2.1 + 2.4 = 9

9/5 = 1.8

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August hosted two dinner parties for his friends. Twenty guests attended the first party, and twenty-six guests attended the second party. What is the percentage increase of the number of guests from the first party to the second party?
Find the missing coefficient. -___________ y2 − [-5y − y(-7y − 9)] − [-y (15y + 4)] = 0

If AABC is reflected across the yaxis, what are the coordinates of A?I need the answer G to graduate

Answers

Answer:

A lies on (1,3) a reflection across the y-axis is (x,y) to (-x,y). The x turns the opposite and y stays the same so...

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Which is a true statement? A. –11.6 > 7.52 B. –5.39 > –4.21 C. 8.7 < 8.63 D. –6.29 < –4.81

Answers

Well first lets review the information on these numbers. A negative number is less than 0. So the bigger the negative number, the smaller it actually is.

So...

a) -11.6 > 7.52 (A negative is not greater than a positive!)
b) -5.39 > -4.21 (The bigger the negative the smaller the number -Nope!)
c) 8.7 < 8.63 (Nope- you can tell just by knowing the common number)
d) -6.29 < -4.81 (YES!!)

hope that helps!
D.
A negative number is smaller than a positive number... but as the negative numbers begin to use the larger digits that means that the number is smaller (it's backwards to counting in positive)... think of it like a mirror :) Hope this helps 

in a class 60% of the students are girls there are 18 girls in the class. how many students are in the class and how many boys are in the class? Show Work

Answers

There are 30 students and 12 boys
60%-------> 18
40℅------>?
100%------>?

to find the answers first divide 18 by 60=0.3, now we know the number for 1%
now workout the 40% by multiplying it by 40%
0.3×40= 12
so the number of boys is 12
to find the total add the no. boys and girls.
12+18=30 so the total number of pupils is 30.

hope it helps

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Answers

The answer is Y=6x-2

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Answers

y and x are the two varibles so 5 and 10 are your contants

Consider the system below. 4x-2y=-12 3x-y=-3 Solve the system by using a matrix equation. Show your work.

Answers

The matrix equation AX=B, where A and B are numerical matrices and X is unknown matrix has a solution X= A^(-1) B, where A^(-1) is inverse matrix of X.
1. We rewrite given system as matrix equation \left[\begin{array}{cc}4&-2\n3&-1\end{array}\right] X=\left[\begin{array}{c}- 12\n- 3\end{array}\right];
2. FindA^(-1) = \left[\begin{array}{cc}4&-2\n3&-1\end{array}\right] ^(-1)  by the rule A^(-1)= (1)/(det \ A) [ A_(ij) ] ^(T). So, det\ A=4×(-1)-3×(-2)=-4+6=2 and algebraic supplements are
A_(11) =-1 \n A_(12) =-3 \n A_(21)=2 \n A_(22) =4. Then A^(-1) = (1)/(2) \left[\begin{array}{cc}-1&-3\n2&4\end{array}\right] ^(T)= \left[\begin{array}{cc}- (1)/(2) &1\n- (3)/(2) &2\end{array}\right];
3. Calculate X= \left[\begin{array}{cc}- (1)/(2) &1\n- (3)/(2) &2\end{array}\right] \left[\begin{array}{c} -12\n-3\end{array}\right]=\left[\begin{array}{c}3\n12\end{array}\right];

4. We obtain X= \left[\begin{array}{c}3\n12\end{array}\right], from where x=3 and y=12.
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