We can solve this by substitution method.
Look at the second equation. If we rearrange to find 7x, we can substitute in the value into the first equation.
[tex]5y-7x=12[/tex]
[tex]5y-7x-12=0[/tex]
[tex]5y-12=7x[/tex]
Therefore, [tex]7x=5y-12[/tex]
Now replace the 7x in the first equation with 5y - 12:
[tex]2y+7x=-5[/tex] (substitute in 7x = 5y - 12)
[tex]2y+(5y-12)=-5[/tex]
[tex]7y-12=-5[/tex]
[tex]7y=7[/tex]
[tex]y=1[/tex]
Now that we know y, we can find x by substituting in y = 1 into any equation we want. I will use the equation: 7x = 5y - 12
[tex]7x=5y-12[/tex] (substitute in y = 1)
[tex]7x=5(1) -12[/tex]
[tex]5x=5-12[/tex]
[tex]7x=-7[/tex]
[tex]x=-1[/tex]
__________________________________________________________
Answer:
[tex]y=1\\x=-1[/tex]
The U.S. Department of Agriculture records data on farm acreage and number of farms by county for every county in the country. This takes considerable time and energy, and the results for each update (usually occurring approximately every five years) are a long time in process. A quicker way to update the data is by sampling. The table below shows the number of counties in each geographic region and a summary of farm acres (in thousands) for independent random samples of 22 counties from each region.
Region Number of counties
North Central 1052
North East 210
South 1376
West 418
Required:
a. Estimate the mean acreage for each region, with a margin of error.
b. Estimate the total acreage for each region, with a margin of error.
c. Estimate the difference between mean acreage for the North Central region and the South, with a margin of error.
d. Estimate the difference between mean acreage for the North East and the West, with a margin of error.
e. Estimate the mean acreage per county across the United States, with a margin of error.
Solution :
From the table,
Number of countries = [tex]$N_i$[/tex]
Mean = [tex]$\overline Y_i$[/tex]
Standard deviation = [tex]$\sigma_i$[/tex]
Margin of error of B = 50,000 acres
So we determine the [tex]$\text{sample size n}$[/tex] and then allocate the four regions of [tex]$n_1, n_2, n_3$[/tex] and [tex]$n_4$[/tex].
Under the [tex]$\text{proportional allocation}$[/tex], the [tex]$\text{equation}$[/tex] for the value of [tex]$n_1$[/tex] which yields [tex]$V(\overline Y_{st}) = D = \frac{B^2}{H}$[/tex] is given by :
[tex]$n=\frac{\sum_{K=1}^L N_K \sigma^2_K}{ND+\frac{1}{N}\sum_{K=1}^L N_K \sigma^2_K}$[/tex]
Let us complete the numerator
[tex]$\sum_{K=1}^L N_K \sigma^2_K = N_1\sigma_1^2 + N_2\sigma_2^2 + N_3\sigma_3^2 + N_4\sigma_4^2$[/tex]
[tex]$= 1052 \times (271)^2 + 210 \times (79)^2 + 1376 \times (244)^2 + 418 \times (837)^2 $[/tex]
= 453329920
The bound on the error of estimation is B = 50,000 acres
Hence we get
[tex]$D=\frac{B^2}{H}$[/tex]
[tex]$=\frac{50000^2}{4}$[/tex]
= 625,000,000
[tex]$n=\frac{\sum_{K=1}^L N_K \sigma^2_K}{ND+\frac{1}{N}\sum_{K=1}^L N_K \sigma^2_K}$[/tex]
[tex]$=\frac{453329920}{3056 \times 625 + \frac{1}{3056} \times 453329920}$[/tex]
= 220.24044
≈ 221 (approximately)
Therefore, the sample size under the proportional allocation from each stratum are given by :
[tex]$n_1=n\left[\frac{N_1}{\sum_{K=1}^\mu N_K}\right]$[/tex]
[tex]$=221\left[\frac{1052}{3056}\right]$[/tex]
≈ 76
[tex]$n_2=n\left[\frac{N_2}{\sum_{K=1}^\mu N_K}\right]$[/tex]
[tex]$=221\left[\frac{210}{3056}\right]$[/tex]
≈ 15
[tex]$n_3=n\left[\frac{N_3}{\sum_{K=1}^\mu N_K}\right]$[/tex]
[tex]$=221\left[\frac{1376}{3056}\right]$[/tex]
≈ 100
[tex]$n_4=n\left[\frac{N_4}{\sum_{K=1}^\mu N_K}\right]$[/tex]
[tex]$=221\left[\frac{418}{3056}\right]$[/tex]
≈ 30
Thus, we should select 76 counties from North central region, 15 counties from the north east region, 100 from south region and 30 from west region.
We can also estimate mean acreage of each county across all the county with a margin of error of 50,000 acres.
1 gold plate weight 30 mg if the weight of some plates is 450 ml mg find the number of plates
Answer:
15 plates
Step-by-step explanation:
450 divided by 30 = 15, meaning 30 x 15 would be 450 mg. This also means that if the weight of some plates was 450 mg, there would be 15 plates.
Answer:
15
Step-by-step explanation:
Your units are a little confused.
The mass (total ) is 450 mg
1 plate weighs 30 mg
1 plate / 30 mg = x plates / 450 mg Cross multiply
1 * 450 = 30x Divide by 30
450 / 30 = x
x = 15
There are 15 gold plates.
Given the function h(x)=-x^2-5x+14 determine the average rate of change of the function over the interval -9
Answer:
The average rate of change of the function over the interval is of 6.
Step-by-step explanation:
Average rate of change:
The average rate of change of a function h(x) over an interval [a,b] is given by:
[tex]A = \frac{h(b)-h(a)}{b-a}[/tex]
In this question:
Over the interval [-9,-2], so [tex]a = -9, b = -2, b - a = -2 -(-9) = 7[/tex]
The function is:
[tex]h(x) = -x^2 - 5x + 14[/tex]
[tex]h(-9) = -9^2 -5(-9) + 14 = -81 + 45 + 14 = -22[/tex]
[tex]h(-2) = -2^2 -5(-2) + 14 = -4 + 10 + 14 = 20[/tex]
Then
[tex]A = \frac{h(-2)-h(-9)}{7} = \frac{20-(-22)}{7} = \frac{42}{7} = 6[/tex]
The average rate of change of the function over the interval is of 6.
what is the additive inverse of the complex number 9-4i?
B on edg
-9+4i
Answer:
-9 + 4i
Step-by-step explanation:
The additive inverse ("opposite") of a complex number a + bi is -a - bi.
Just use the opposites of a and b.
A flood lamp is installed on the ground 200 feet from a vertical wall. A six-foot-tallman is walking towards the wall at the rate of 30 feet per second. How fast is the tip of his shadow moving down the wall when he is 50 feet from the wall
Answer:
The rate at which the tip of his shadow is moving down is [tex]\frac{24}{15} ft/sec[/tex]
Step-by-step explanation:
Given - A flood lamp is installed on the ground 200 feet from a vertical wall. A six-foot-tall man is walking towards the wall at the rate of 30 feet per second.
To find - How fast is the tip of his shadow moving down the wall when he is 50 feet from the wall ?
Proof -
From the given information, the figure becomes
Triangle ABC and Triangle DBE are similar triangle
AC/DE = BC/BE
⇒h/6 = 200/(200-x)
⇒h = 1200/(200 -x)
Now,
Differentiate h with respect to t, we get
[tex]\frac{dh}{dt} = 1200(-\frac{1}{(200-x)^{2} } )(-1)\frac{dx}{dt}[/tex]
⇒[tex]\frac{dh}{dt} = (\frac{1200}{(200-x)^{2} } )\frac{dx}{dt}[/tex]
Now,
If the rate of the tip is moving down the wall
At x = 50 feet, dx/dt = 30 feet per second
So,
⇒[tex]\frac{dh}{dt} = (\frac{1200}{(200-50)^{2} } )(30)[/tex]
⇒[tex]\frac{dh}{dt} = \frac{1200}{(150)^{2} } (30)[/tex]
⇒[tex]\frac{dh}{dt} = \frac{1200}{(150)(150) } (30)[/tex]
⇒[tex]\frac{dh}{dt} = \frac{24}{15 }[/tex]
So, we get
The rate at which the tip of his shadow is moving down is [tex]\frac{24}{15} ft/sec[/tex]
suzanne babysits to earn extra money. she charges $15 for each hour that she babysits. What represents the independent variable in this situation?
A. The total amount charged for babysitting
B. The rate she us paid per hour
C. The number of hours she babysits
D. The number of children she babysits
Answer:
C. The number of hours she babysits
Step-by-step explanation:
In this situation, the number of hours she babysits is the independent variable.
This is because it will directly influence the amount of money that she earns, which is the dependent variable.
For example, working for 1 hour will earn her $15.
So, the correct answer is C. The number of hours she babysits
Which of the pairs of angles are vertical angles and thus congruent? ∠A and ∠G ∠A and ∠B ∠C and ∠F ∠D and ∠H
Answer:
∠A and ∠G is the pair of vertical angles.
Step-by-step explanation:
From the figure attached,
Two lines 'm' and 'n' are two parallel lines. These lines intersect a horizontal line 'l'.
Since, "Pair of opposite angles formed at the point of intersection are the vertical angles and equal in measure."
Therefore, Opposite angles ∠A ≅ ∠G, ∠B ≅ ∠H, ∠C ≅ ∠E and ∠D ∠F are the vertical angles.
From the given options,
∠A and ∠G is the pair representing the pair of vertical angles and thus congruent.
Answer:
∠A and ∠G
Step-by-Step Explaination:
I did it on
E
D
G
E
N
U
I
T
Y
(a) 34 is 85% of what number?
Answer:
[tex]40[/tex]
hope this helps you.
Can I have the brainliest please?
WILL GIVE BRAINLIEST!!!!
Plot the image of quadrilateral ABCD under a reflection across line L.
Answer:
See image
Step-by-step explanation:
I clicked submit and it was right
Also dude I remember doing this and struggling before
The point (-8,0) reflected in the x-axis is
Answer:
That would be (8,0) my good sir ( ma'am )
Step-by-step explanation:
Have a nice day
Can somebody please help in this question?
First find the area of one side.
The area of the side of a cube is s^2 where s is the length if one edge.
The edge length is given as 2/3, so the area of a side is 2/3^2 which is equal to 2/3 x 2/3 = 4/9 square units.
A cube has 6 sides so now to find the surface area of the cube multiply the area of one side by 6 sides:
4/9 square units x 6 = (4 x6)/9 = 24/9 which can be rewritten as 2 2/3 square units
The answer is 2 2/3 units^2
If using the method of completing the square to solve the quadratic equation x2+14x-14=0, which number would have to be added to "complete the square"?
Answer:
49
Step-by-step explanation:
the number would simply be
14÷2=7
7²=49
If 2x + 5 = 82, then 12x = ?
A 5
B
10
C 15
D 20
Answer:
2x= 38.5
Step-by-step explanation:
I'm not sure where u got 12x but 2 x = 38.5:
2x + 5 =82
subtract 5 for 82
2x = 77
77 divided by 2 is 38.5
x = 38.5
hope this helps :)
A dilation has center at the origin. Which of the following is the image of the point P(1.- for a scale
factor of
A
D: (P) = P(x3)
B
D}(P) = P',
C
D:(P) = P1C-
D
D}(P) = PG-)
Answer:
C. [tex]D_\frac{1}{7} (P)=P'(\frac{1}{4},-\frac{5}{14} )[/tex]
Step-by-step explanation:
[tex]\frac{7}{4}*\frac{1}{7}=\frac{7}{28} =\frac{1}{4}[/tex]
[tex]-\frac{5}{2} *\frac{1}{7} =-\frac{5}{14}[/tex]
7k-6,2k+14 solve for K
Answer:
0.8k +14
Step-by-step explanation:
See the steps below:)
A circle has radius 6 cm. Suppose an arc on the circle has length 31 cm. Answer the
following:
a. The fraction of the whole circle represented by this arc is
b. The measure of the central angle defined by the arc is
degrees.
C. The area of the sector defined by the arc is
cm2. (Express answer
in terms of r or pi).
Answer:
[tex]Fraction = \frac{31}{38}[/tex]
[tex]\theta = 296.18^\circ[/tex]
[tex]Area = 29.62 \pi[/tex]
Step-by-step explanation:
Given
[tex]r = 6[/tex]--- radius
[tex]L = 31[/tex] --- arc length
Solving (a): Fraction represented by the arc
First, calculate the circumference (C)
[tex]C = 2\pi r[/tex]
So, we have:
[tex]C = 2 * 3.14 * 6[/tex]
[tex]C = 38[/tex] --- approximated
So, the fraction represented by the arc is:
[tex]Fraction = \frac{L}{C}[/tex]
[tex]Fraction = \frac{31}{38}[/tex]
Solving (b): Measure of the center angle
Using arc length formula, we have:
[tex]L = \frac{\theta}{360} * 2\pi r[/tex]
This gives
[tex]31 = \frac{\theta}{360} * 2 * 3.14 * 6[/tex]
[tex]31 = \frac{\theta}{360} * 37.68[/tex]
Make [tex]\theta[/tex] the subject
[tex]\theta = \frac{360 * 31}{37.68}[/tex]
[tex]\theta = 296.18^\circ[/tex]
Solving (c): The area of the sector
This is calculated as:
[tex]Area = \frac{\theta}{360} * \pi r^2[/tex]
So, we have:
[tex]Area = \frac{296.18}{360} * \pi * 6^2[/tex]
[tex]Area = \frac{296.18}{360} * \pi * 36[/tex]
Divide 360 and 36
[tex]Area = \frac{296.18}{10} * \pi[/tex]
[tex]Area = 29.618 * \pi\\[/tex]
[tex]Area = 29.62 \pi[/tex] --- approximated
please help
thank you
Answer:
Step-by-step explanation:
-4<n≤5
which of the following represents the equality for the sum of 11 and Y is greater than -33
Answer:
11+y > -33
Step-by-step explanation:
Answer:
You wrote
"Which of the following" Meaning there's should be options present.
But Going with the statement...
The sum of 11 and y is greater than -33
I'd say
11 + y > -33.
Are the fractions 2/8 and 1/4 equivalent ? True or False?
Answer:
True
Step-by-step explanation:
Equivalent fractions are fractions with different numbers representing the same part of a whole.
Express 848.41 m in millimeters
50 POINTS
Solve by linear combination
2x-4y=4
x-4y=10
Write your answer as an ordered pair with no spaces (x,y)
Answer:
(1/2,1/4) because m= 1/5 and m= 1/2 and te equation is y=1/4x - 5/2 and y= 1/2x - 1
Substracting both
[tex]\\ \sf\Rrightarrow x=4-10=-6[/tex]
Putting in eq(2)
[tex]\\ \sf\Rrightarrow -6-4y=10[/tex]
[tex]\\ \sf\Rrightarrow -4y=16[/tex]
[tex]\\ \sf\Rrightarrow y=-4[/tex]
Hence our solution is
(x,y)=(-6,-4)HELP ASAP!!!!!!
Colin saved $30 in July, $21.50 in August, and $50 in September. He spent $18 on video games and $26.83 on books. How much money does Colin have left?
I have no idea pls help
Answer:
Area= 90
Step-by-step explanation:
triangle area: (b x h) / 2
(12 x 15) / 2
(180) / 2
a= 90
Donna is participating in a 6-day cross-country biking challenge. She biked for 51, 62, 61, 47, and 63 miles on the first five days. How many miles does she need to bike on the last day so that her average (mean) is 56 miles per day?
Answer:
52 miles
Step-by-step explanation:
total miles needed to average 56
56 * 6 = 336
miles after 5 days
51 + 62 + 61 + 47 + 63 = 284
miles needed on last day
336 - 284 = 52 miles
Was Thomas Jefferson a federalist or anti-federalist?
Answer:
He was an Anti-federalist
Step-by-step explanation:
Answer:
Anti-federalist
Step-by-step explanation:
The Federalists, led by Secretary of Treasury Alexander Hamilton, wanted a strong central government, while the Anti-Federalists, led by Secretary of State Thomas Jefferson, advocated states' rights instead of centralized power.
1 hundredth + 3 tenths =?hundredths
Answer:
.01 + .3 = 0.31
Step-by-step explanation:
I need this please ya
GE = 26
Step-by-step explanation:
OP = 16 + 9 = 25
PE - OG = 7
Using Pythagorean theorem,
(GE)^2 = (OP)^2 + (PE - OG)^2
=(25)^2 + (7)^2
= 625 + 49
= 674
or
GE = √674 = 25.96 or 26
can someone help me.?!
[tex]{\boxed{\mathcal{\red{h\:=\:9.5}}}}[/tex] ✅
Step-by-step explanation:-[tex]h + \frac{1}{2} = 10 \\ ⇢ h + 0.5 = 10 \\ ⇢ h \: = 10 - 0.5 \\ ⇢ h = 9.5[/tex]
[tex]\circ \: \: { \underline{ \boxed{ \sf{ \color{green}{Happy\:learning.}}}}}∘[/tex]
The question is ...(see the picture)
Thank you very much！！
Answer: [tex]3x^{-2.5}[/tex]
Step-by-step explanation:
Given
Expression is
[tex]\dfrac{12\sqrt{x}}{4x^3}[/tex]
Using exponent property [tex]x^a\cdot x^b=x^{a+b}[/tex]
Writing expression in the form of [tex]k\cdot x^n[/tex]
[tex]\Rightarrow \dfrac{12\sqrt{x}}{4x^3}=\dfrac{3\times 4}{4}\times \dfrac{x^{0.5}}{x^3}\\\\\Rightarrow \dfrac{3\times 4}{4}\times x^{0.5-3}\\\\\Rightarrow 3x^{-2.5}[/tex]
Find the quotient for 5,600÷8
Answer:
700
Hope this helps!!
Answer:
700
Step-by-step explanation: