He answered 16 questions correctly, and got 3 wrong answers.
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Explanation:
Let
x = number of questions that are correct y = number of wrong answers z = number of questions left blankx,y,z are nonnegative whole numbers.
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Since there are 20 questions total, this means the first equation to set up is:
x+y+z = 20
Solving for y leads to
x+y+z = 20
y+z = 20-x
y = 20-x-z
We'll use this later.
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Another equation to set up is 7x-4y = 100 because Eric earns 7 points per correct answer and loses 4 points for each incorrect answer, and all that leads to 100 points total which was his quiz score. We'll ignore the questions he left blank since they add 0 points.
Let's plug the equation in which we isolated y
7x-4y = 100
7x-4(20-x-z) = 100
7x-80+4x+4z = 100
7x+4x+4z = 100+80
11x+4z = 180
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Now we can guess and check to see which pair of x and z values will make that last equation above true. I suggest starting with the smallest possible value of x and using that x value to solve for z.
If x = 0, then,
11x+4z = 180
11(0)+4z = 180
4z = 180
z = 180/4
z = 45
So if Eric got 0 correct answers, then he left 45 questions blank. But that isn't possible because there are only 20 questions total. So we'll ignore the case that x = 0.
If we increase x by 4, and decrease z by 11, then we get another ordered pair solution to this equation
So another solution is (x,z) = (4,34)
Note that
11x+4y = 180
11(4) + 4(34) = 180
But like before, z = 34 isn't possible since 20 is the max.
Increase x by 4 again, and drop z by 11 to get (x,z) = (8,23). Again we run into the same issue as before.
Increase x by 4 again, and decrease z by 11 to get (x,z) = (12, 12). Now we have both x and z smaller than 20, but note how x+z = 12+12 = 24 which exceeds the total number of questions. So we rule this case out as well.
Do another round of "increase x by 4, decrease z by 11" to get to (x,z) = (16, 1). This is the only case left because anything beyond this, z will be negative.
Luckily, this final case does work. If Eric answers x = 16 questions correctly, then he left z = 1 of them blank. That must mean y = 20-x-z = 20-16-1 = 3 questions were incorrect.
We can see that:
7x-4y = 7(16)-4(3) = 112-12= 100
meaning that (x,y) = (16,3) is a solution to 7x-4y = 100.
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To summarize, we found that the only possible solution is (x,y,z) = (16, 3, 1)
Meaning x = 16 questions were correct, y = 3 were wrong, and z = 1 question was left blank.
Good morning, can someone help me solve this problem? I already did some of it but I need help, thank you
Answer: (-4, -1)
This means x = -4 and y = -1 pair up together.
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You're on the right track. You'll replace the 'x' with 3y-1, but you made a typo. I think you meant to write the subtraction symbol instead of the equal sign.
Here's what your steps could look like
-2x + 5y = 3
-2(3y-1) + 5y = 3
-6y + 2 + 5y = 3
-y + 2 = 3
-y = 3-2
-y = 1
y = -1
x = 3y-1
x = 3(-1) - 1
x = -3-1
x = -4
Therefore, (x, y) = (-4, -1) is the solution
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As the steps above show, I replaced each copy of x in the second equation with (3y-1). This is due to x = 3y-1. From there, we isolate y. Once you determine that y = -1, it's plugged into the first equation to find x.
If you were to graph x = 3y-1 and -2x+5y = 3 on the same xy coordinate grid, then the two lines would intersect at (-4, -1)
Also, note how plugging x = -4 and y = -1 into the second equation leads to...
-2x+5y = 3
-2(-4)+5(-1) = 3
8 - 5 = 3
3 = 3
We get the same value on both sides, so that verifies the second equation. I'll let you verify the first equation.
PLZ HELP ME GUYS
Jsjsjsjshs
when the “a” value is negative in any quadratic what do you know about the graph?
Answer:
when a is negative, the parabola opens downward
Step-by-step explanation:
can someone please pls help me
The measure of an angle is 2.8.what is the measure of its complementary angle
Answer:
87.2º
Step-by-step explanation:
Complimentary angles total 90º
c + 2.8 = 90
c = 90 - 2.8
c = 87.2º
Answer:
87.2°Step-by-step explanation:
When angles are complementary, it means that they both add up to 90°.
In this case, one of the angles measures 2.8°.
So, to find the other one, we subtract 2.8 from 90.
90 - 2.8 = 87.2
The measure of the complementary angle is 87.2°
I hope this helps! I would really appreciate it if you would please mark me brainliest! Have a blessed day!
A ____ can be observed by all people on the side of the earth experiencing night. Group of answer choices Solar Eclipse Sunrise Lunar Eclipse Gravitation attraction of the sun
Answer:
Lunar Eclipse
Step-by-step explanation:
Lunar eclipse is the phenomenon that occurs on the night of the full moon. During this phenomenon the Earth comes in between the Sun and the Moon. The Earth blocks the light of the Sun with which the Moon is visible to the people on the Earth. Lunar Eclipse is visible from the part of the Earth that is experiencing the night. The duration of the Lunar eclipse can be for two hours. The moon appears to be red because of the reflection of the Earth.
Marulla's z score on a college entrance exam is 1.3. If the raw scores have a mean of 480 and a standard deviation of 70 points, what is her raw score?
Answer:
571
Step-by-step explanation:
We solve using z score.
z = (x-μ)/σ, where
x is the raw score = ?
μ is the population mean = 480
σ is the population standard deviation = 70
z = 1.3
Hence,
= 1.3 = x - 480/70
Cross Mulitiply
1.3 × 70 = x - 480
91 = x - 480
x = 480 + 91
x = 571
Therefore, Marulla's raw score is 571
A clothing store donated a percent of every sale to charity. The total sales were $8850, so the store donated $531 what percent of $8850 was donated to charity?
Answer:
6%
Step-by-step explanation:
[tex]\frac{531}{8850} *\frac{x}{100} \\531*100= 5310053100/8850= 6%[/tex]
Can somebody help me with writing a real-life problem on this subject Finding angle measures of a right or isosceles triangle given angles with variables thank you?
Answer:
See Explanation
Step-by-step explanation:
See attachment for illustration
(a) Right triangle
The sum of [tex]angles[/tex] in a [tex]right[/tex] [tex]triangle[/tex]is:
[tex]x + y + 90 = 180[/tex]
Subtract 90 from bot sides
[tex]x + y = 90[/tex]
Make x the subject
[tex]x = 90 - y[/tex]
Make y the subject
[tex]y = 90 - x[/tex]
This implies that, subtract the known angle from 90 to get the unknown angle.
Assume [tex]x = 40[/tex]
We make use of: [tex]y = 90 - x[/tex]
[tex]y = 90 - 40 = 50[/tex]
(b) Isosceles triangle
The sum of angles in an isosceles triangle is:
[tex]x + y + y = 180[/tex] ---- y appear twice because the base angles are equal
[tex]x + 2y = 180[/tex]
Make x the subject
[tex]x = 180 - 2y[/tex]
Make y the subject
[tex]y = \frac{180 - x}{2}[/tex]
Assume [tex]x = 40[/tex], we make use of:
[tex]y = \frac{180 - x}{2}[/tex]
[tex]y = \frac{180 - 40}{2}[/tex]
[tex]y = \frac{140}{2}[/tex]
[tex]y = 70[/tex]
Assume [tex]y = 70[/tex], we make use of:
[tex]x = 180 - 2y[/tex]
[tex]x = 180 - 2 * 70[/tex]
[tex]x = 180 - 140[/tex]
[tex]x = 40[/tex]
r s + 14s when r=6 and s=1/4
Sally can run 5 km in 25 minutes. At the same rat of speed, how far can she run in 2 hours and five minutes?
Answer:
25 km
Step-by-step explanation:
[tex]\frac{5}{25} :\frac{y}{125}[/tex]
y · 25 = 5 · 125
25y = 625
25y ÷ 25 = 625 ÷ 25
y = 25
Five boys each have 8 marbles. If all
their marbles are collected and placed
into
8heaps, how many marbles will there be in each jeap ?
5 marbles.
We first need to find how many marbles we have in total.
8 marbles * 5 boys = 40 marbles.
These 40 marbles will now be divided by 8, since we are taking the total amount of marbles we have and separating them into 8 different piles.
40/8 = 5
There will be 5 marbles in each heap.
The ages of eight different students in a college math class were used to make the box plot shown above. Which of the following numbers below is the median of the ages?
A. 21.5
B. 20.5
C. 22.5
D. 24.5
There is a photo. No explanation needed just answer thank you
Elisa y Romina tienen 5/8 de pizza y decidieron dividírsela en partes iguales. ¿Qué parte de la pizza completa le tocó a cada una?
Answer:
Elisa y Romina comieron 5/16 de la pizza completa cada una.
Step-by-step explanation:
Dado que Elisa y Romina tienen 5/8 de pizza y decidieron dividírsela en partes iguales, para determinar qué parte de la pizza completa le tocó a cada una se debe realizar el siguiente calculo:
(5/2) / 8 = X
2.5 / 8 = X
0.3125 = X
0.3125 = 5/16
Por lo tanto, Elisa y Romina comieron 5/16 de la pizza completa cada una.
There are 19 birds in a pond, all of which are ducks or geese. If the number of ducks in the pond is 1 more than twice the number of geese in the pond, how many geese are in the pond?
A. 6
B. 9
C. 10
D. 13
d I think d
Step-by-step explanation:
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It rains 7 out of every 10 days.
What is the chance of rain on one day?
Answer:
if it rains 7 out of 10 days the chance of rain for one day is 70%
Step-by-step explanation:
A bag contains 9 marbles: 3 are green, 4 are red, and 2 are blue. Teresa chooses a marble at random, and without putting it
back, chooses another one at random. What is the probability that the first marble is blue and the second is green? Write
your answer as a fraction in simplest form.
Answer:
Probability[First marble blue, second is green without replacement] = 1/12
Step-by-step explanation:
Given:
Number of green marble = 3
Number of red marble = 4
Number of blue marble = 2
Total marble = 9 marble
Find:
Probability[First marble blue, second is green without replacement]
Computation:
Probability of an event = Number of favorable outcome / Number of total outcome
Probability[First marble blue] = 2 / 9
Probability[second is green] = 3 / [9-1]
Probability[second is green] = 3 / 8
Probability[First marble blue, second is green without replacement] = Probability[First marble blue] x Probability[second is green]
Probability[First marble blue, second is green without replacement] = [2/9][3/8]
Probability[First marble blue, second is green without replacement] = 6 / 72
Probability[First marble blue, second is green without replacement] = 1/12
The axis of symmetry for the graph of the function f(x)=3x2+bx+4 is What is the value
of b?
-18
-9
9
18
Answer:
B.) -9
Step-by-step explanation:
The value of b if 3/2 is the axis of symmetry for the graph of the function f(x)=3x2+bx+4 is -9
How to calculate the axis of symmetry of a function?The standard equation of a function in vertex form is given as:
f(x) = (a + x)^2 + h
Given the function f(x)=3x^2+bx+4 with an axis of symmetry of 3/2, the vertex is expressed as:
3/2= -b/2a
-b/2(3)=3/2
-b/6=3/2
Cross multiply
-2b = 18
-b=9
Hence the value of b if 3/2 is the axis of symmetry for the graph of the function f(x)=3x2+bx+4 is -9
Learn more on axis of symmetry here: https://brainly.com/question/21191648
A farmer has 200 feet of fencing to use for a chicken pen. He wants the width of the pen to be 27 feet. What will the length be?
Answer:
Length will be 173
Step-by-step explanation:
√320x^3 yz
simplify square roots
Answer:
[tex]8x\sqrt{5x}[/tex]yz
Step-by-step explanation:
before you plug in this answer, is your correct equation [tex]\sqrt{320x^3} yz[/tex] or [tex]\sqrt{320x^3yz}[/tex]
The number of miles a car travels varies directly with the number of gallons of gas in its tank of a car with 20 gallons of gas can drive 560 miles which equation represents the number of miles an
Answer:
28 miles per gallon
560/20=28
Step-by-step explanation:
Plz give me brainliest
Number of miles a car travels are 28.
What is division?The division is the process of repetitive subtraction. It is the inverse of the multiplication operation. It is defined as the act of forming equal groups. While dividing numbers, we break down a larger number into smaller numbers such that the multiplication of those smaller numbers will be equal to the larger number taken.
Number of gallons of gas = 20
A car with 20 gallons of gas can drive 560 miles
Based on the given conditions,
= [tex]\frac{560}{20}[/tex]
= 28
Hence, number of miles are 28.
Find out more information about division here
https://brainly.com/question/10850080
#SPJ2
(1 point) Find ⋅ if =⟨−1,0,1⟩ and =⟨4,5,2⟩ Is the angle between the vectors "acute", "obtuse" or "right"?
Answer:
Obtuse.
Step-by-step explanation:
If we have a vector v = (a, b, c)
The magnitude of the vector is:
|v| = √(a^2 + b^2 + c^2)
And the dot product of two vectors:
v = (a, b, c)
w = (c, d, e)
is:
v.w = |v|*|w|*cos(θ) = a*c + b*d + c*e
With that relation, we can find the angle between the two vectors.
In this case, we have:
v = ⟨−1,0,1⟩
then:
|v| = √( (-1)^2 + 0^2 + 1^2) = √2
And:
w = ⟨4,5,2⟩
then:
|w| = √( 4^2 + 5^2 +2^2) = √116
Then:
v.w = (√2)*(√116)*cos(θ) = (-1)*(4) + 0*5 + 1*2
(√2)*(√116)*cos(θ) = -4 + 2 = -2
(15.23)*cos(θ) = -2
cos(θ) = -2/15.23
θ = Acos( -2/15.23) = 97.5°
Then the angle is larger than 90°, so the angle is obtuse.
5. (08.01) Line M is represented by the following equation: x + y = -1 What is most likely the equation for line P so the set of equations has infinitely many solutions?
O 2x + 2y = 2
O 2x + 2y = 4
O 2x + 2y = -2
O x - y = 1
Answer:
2x + 2y = -2
Step-by-step explanation:
you can divide a 2 from all three terms in 2x + 2y = -2 to get x + y = -1 which overlaps the original equation to provide an infinite number of solutions
Maya invests $3,500 into an ETF which earns 7% per year. In
30 years, how much will Maya's investment be worth if
interest is compounded semiannually (twice a year)? Round to
the nearest dollar.
As Soon As Possible! (please)
Each day a supernatural termite can eat 35% more wood grains that it did the day before. If a 20-day old termite has eaten 97,231 grains of wood, how many wood grains (to the nearest grain) will it eat on the 22nd day?
A) 84 grains
B) 130,745 grains
C) 176,589 grains
D) 235,768 grains
I need help ASAP! 20 point
I’m the xy-plane, a line has a slope of 6 and passed through the point (0,8). Which of the following is an equation of this line?
Answer:
A) y = 6x + 8
Step-by-step explanation:
HELPPPPPP
solve the equation for x
2/3x-1/9x+5=20
Answer:
x=27
Step-by-step explanation:
You want to isolate the variables so you subtract 5 from both sides. Therefore the equation will be 2/3x-1/9x=15. You want to take away the fraction because no one likes fractions. You have to multiply everything by 9. Therefore, the equation will be 6x-x=135. 5x=135. You want to isolate x so you have to divide each side by 5. x=135/5. Simplify to get x=27.
If this has helped you please mark as brainliest
Which equation models this situation? 26 more than a number is 37.
Answer:
x+26=37
Step-by-step explanation:
2+2=?
i dont remember this, its too complex for me someone help asap
ahem ahem
2+2=69
it's 4 thanks for the points