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3 years ago

I do not understand this question, anyone help? Most brainiest for the right answer!

Mathematics

1 answer:

Oksi-84 [34.3K]3 years ago

6 0

Answer:

56.7

Step-by-step explanation:

We know

mean = sum / count, with count being the amount of papers corrected in this case. We want to find the sum of all the papers as well as the count to figure out the mean of all papers.

For Tony's papers,

mean = sum / count

50 = sum / 40

multiply both sides by 40 to isolate the sum

sum = 50 * 40 = 2000

For Alice's papers,

mean = sum / count

70 = sum / 20

multiply both sides by 20 to isolate the sum

70 * 20 = sum = 1400

The total sum of all 60 papers is equal to the sum of 40 papers + the sum of the remaining 20 papers, or 2000 + 1400 = 3400. The mean of the 60 papers is therefore

mean = sum / count

mean = 3400/60 ≈ 56.7

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Sylvie finds the solution to the system of equations by graphing.

Softa [21]

Answer:

The correct answer is:

A coordinate grid with 2 lines. The first line passes through the points (negative 1.5, 0), (0, negative 1), and (3, negative 3). The second line passes through the points (negative 1.5, 0), (0, 1), and (3, 3).

Step-by-step explanation:

We are given the system of equations as:

$1.\ y=-\dfrac{2}{3}x-1\\2.\ y=\dfrac{2}{3}x+1\\$

We have 2 equations here with variables x and y so we use coordinate grid with 2 lines having axis as x and y.

As per the given options, we can see that coordinate of one point has y = 0 and other point has x = 0.

So, let us put y = 0 and x =0, in both the equations one by one and have a look at the value of x coordinate.

y = 0, Equation (1) becomes:

$0=-\dfrac{2}{3}x-1\\\Rightarrow 1 =-\dfrac{2}{3}x\\\Rightarrow x = - 1.5$

So, one coordinate is (-1.5, 0)

x = 0, Equation (1) becomes:

$y=-\dfrac{2}{3}\times 0-1\\\Rightarrow y =-1$

So, other coordinate is (0, -1)

And the point (3, -3) also satisfies the given equation.

y = 0, Equation (2) becomes:

$0=\dfrac{2}{3}x+1\\\Rightarrow 1 =-\dfrac{2}{3}x\\\Rightarrow x = - 1.5$

So, one coordinate is (-1.5, 0)

x = 0, Equation (2) becomes:

$y=\dfrac{2}{3}\times 0+1\\\Rightarrow y =1$

So, other coordinate is (0, 1)

And the point (3, 3) also satisfies the given equation.

Please refer to the attached graph and points on lines.

So, correct answer is:

3 0

3 years ago

Read 2 more answers

List the next 4 multiples of the unit fraction 1/2

Bas_tet [7]

1, 4/2, 2, 6/2 just keep multiplying by 1/2

5 0

3 years ago

Read 2 more answers

What is the value of 4*(-1+2-3+4-3+6-7+....+100) Show your work. [Pls help I am really drowning in work. 50 points + brainliest

KengaRu [80]

Answer:

200

Step-by-step explanation:

We have:

$4(-1+2-3+4-5+6-7...+100)$

We can rearrange the numbers to obtain:

$4((-1-3-5-7-...-99)+(2+4+6...+100))$

From the left, we can factor out a negative. So:

$4(-(1+3+5+7+...+99)+(2+4+6...+100))$

In other words, we want to find the sum of all the odd numbers from 1 to 99.

And the sum of all the even numbers from 2 to 100.

Let's do each one individually:

Odd Terms:

We have:

$(1+3+5+7+...+99)$

We can use the arithmetic series formula, where:

$S=\frac{k}{2}(a+x_k)$

Where k is the number of terms, a is the first term, and x_k is the last term.

Since it's all the odd numbers between 1 and 99, there are 50 terms.

Our first term is 1 and our last term is 99. So, the sum of all the odd terms are:

$S=\frac{50}{2}(1+99})$

Divide the fraction. Add within the parentheses:

$S=25(100)$

Multiply:

$S=2500$

So, the sum of all the odd terms is 2500.

Even Terms:

We have:

$(2+4+6+...+100)$

Again, we can use the above formula.

Our first term is 2, last term is 100. And since it's from 2-100, we have 50 even terms. So:

$S=\frac{50}{2}(2+100)$

Divide and add:

$S=25(102)$

Multiply:

$S=2550$

We originally had:

$4(-(1+3+5+7+...+99)+(2+4+6...+100))$

Substitute them for their respective sums:

$4(-(2500)+2550)$

Multiply:

$4(-2500+2550)$

Add:

$=4(50)$

Multiply:

$=200$

So, the sum of our sequence is 200.

And we're done!

Note: I just found a way easier way to do this. We have:

$4\cdot(-1+2-3+4-5+6-7+...+100)$

Let's group every two terms together. So:

$=4((-1+2)+(-3+4)+(-5+6)...+(-99+100))$

We can see that they each sum to 1:

$=4((1)+(1)+(1)+...+(1))$

Since there are 100 terms, we will have 50 pairs, so 50 times 1. So:

$=4(50)$

Multiply:

$=200$

Pick which one you want to use! I will suggest this one though...

Edit: Typo

8 0

4 years ago

Geometry Work, Confused.

serious [3.7K]

Answer:

Step-by-step explanation:

RST all have 90° but T is the only one that also has 5 so by default it has to be 5

3 0

3 years ago

Find the equation of a line that has the same slope ask why equals 10-4x and the same Y intercept is why equals -9x-8

Alborosie

Answer:

$y=-4x-8$

Step-by-step explanation:

we know that

The equation of the line in slope intercept form is equal to

$y=mx+b$

where

m is the slope

b is the y-intercept

1) Find the slope of the given line $y=10-4x$

The slope is $m=-4$

2) Find the y-intercept of the given line $y=-9x-8$

The y-intercept is $b=-8$

therefore

The equation of the line with

$m=-4$

$b=-8$

is equal to

$y=-4x-8$

3 0

3 years ago