Answer:
0.28
Step-by-step explanation:
The sum of the geometric value progression is S = 0.28
What is Geometric Progression?A geometric progression is a sequence in which each term is derived by multiplying or dividing the preceding term by a fixed number called the common ratio.
The nth term of a GP is aₙ = arⁿ⁻¹
The general form of a GP is a, ar, ar2, ar3 and so on
Sum of first n terms of a GP is Sₙ = a(rⁿ-1) / ( r - 1 )
Given data ,
Let the sequence be A = { 1 - 0.99 + 0.99² - 0.99³... - 0.99⁷⁹ }
So , A = 1 - { 0.99 - 0.99² + 0.99³... + 0.99⁷⁹ }
Let the first term of the GP be a₁ = 0.99
Now , the common ratio of GP , r = 0.99
And , the number of terms in GP = 80
And , Sum of first n terms of a GP is Sₙ = a(rⁿ-1) / ( r - 1 )
On simplifying , we get
S₈₀ = 0.99 ( 1 - 0.99⁸⁰ ) ( 1 - 0.99 )
On further simplification , we get
S₈₀ = 0.7224
So , the sum of the GP is S = 1 - S₈₀ = 0.28
Hence , the sum of GP is 0.28
To learn more about geometric progression click :
https://brainly.com/question/1522572
#SPJ3
Which of the following values of n will result in a true statement when substituted into the given equation? 4n + 9 = 1 A. n = -2 B. n = 2 C. n = 3 D. n = 4
Answer:
A. n = -2
Step-by-step explanation:
A. n = -2
4(-2) + 9 = 1
-8 + 9 = 1
1 = 1
The value of n for which the statement of equation 4n + 9 = 1 holds true is n = -2.
Given an equation:
4n + 9 = 1
There are some given options for the value of n.
It is required to find the value of n, where the statement is true.
A) When n = -2:
4n + 9 = 4(-2) + 9
= 1
B) When n = 2:
4n + 9 = 4(2) + 9
= 17
C) When n = 3:
4n + 9 = 4(3) + 9
= 21
D) When n = 4:
4n + 9 = 4(4) + 9
= 25
Hence the true statement is when n = -2.
Learn more about Equations here :
https://brainly.com/question/29657988
#SPJ2
If the fish tanks dimension are 60 by 15 by 34 and its is completely empty, what volume of water is needed to fill three fourths of the aquarium? Please help
Answer:
22,950 units³
Step-by-step explanation:
All you have to do is:
[tex]\frac{3}{4} *60*15*34=\\45*15*34=\\675*34=\\\\22,950[/tex]
Idk what it is asking.
Answer:
Jumbo burger with fried is 75%
chicken with salad is 65%
Step-by-step explanation:
you first split the burger and sides. You add up the sides to find the salad. Then add up the sides and burgers
Answer:
What is the probability that he order a Jumbo Burger with Regular Fries or a Chicken Sandwich with a Salad? Make an area or tree diagram to help with the problem.
Answer to question: 20% for Jumbo Burger with Regular Fries and 10.5% for Chicken Sandwich with a Salad.
Step-by-step explanation:
You are going to find the probability that he order a Jumbo Burger with Regular Fries or a Chicken Sandwhich with a Salad by using a area model or a tree diagram. Although you ddin't ask me to solve it, I'm gonna help you with it anyways.
Sandwhiches:
50% - Jumbo Burger (JB)
30% - Chicken Sandwich (CS)
20% - Regular Burger (RB)
Sides:
40% - Curly Fries (CF)
35% - Salad (S)
25% - Regular Fries (RF)
Acronyms
Jumbo Burger (JB) + Curly Fries (CF) = JBCF
Jumbo Burger (JB) + Salad (S) = JBS
Jumbo Burger (JB) + Regular Fries (RF) = JBRF
Chicken Sandwich (CS) + Curly Fries (CF) = CSCF
Chicken Sandwich (CS) + Salad (S) = CSS
Chicken Sandwich (CS) + Regular Fries (RF) = CSRF
Regular Burger (RB) + Curly Fries (CF) = RBCF
Regular Burger (RB) + Salad (S) = RBS
Regular Burger (RB) + Regular Fries (RF) = RBRF
Probability of combinations:
JBCF = 0.5 x 0.4 = 0.20
JBS = 0.5 x 0.35 = 17.5
JBRF = 0.5 x 0.25 = 12.5
CSCF = 0.3 x 0.4 = 12
CSS = 0.3 x 0.35 = 10.5
CSRF = 0.3 x 0.25 = 7.5
RBCF = 0.2 x 0.4 = 8
RBS = 0.2 x 0.35 = 7
RBRF = 0.2 x 0.25 = 5
Your tree diagram should look something like this:
CF(40%)- outcome - JBCF (20%)
/
(50%)JB --- S(35%)- outcome - JBS (17.5%)
\
RF(25%)- outcome - JBRF (12.5%)
CF(40%)- outcome - CSCF (12%)
/
(30%)CS --- S(35%)- outcome - CSS (10.5%)
\
RF(25%)- outcome - CSRF (7.5%)
CF(40%)- outcome - RBCF (8%)
/
(20%)RB --- S(35%)- outcome - RBS (7%)
\
RF(25%)- outcome - RBRF (5%)
Hope this helps because this took forever :D
Talia is going to put a new carpet in her house. She measure's one side of her living room and finds it measures 17 meters which measurement does 17 meters represent
The answer in length
The length is used to measure the distance between to end points or edges. so 17 meters measurement represent the length.
What is perimeter?Its the sum of length of the sides used to made the given figure.
Talia is going to put a new carpet in her house. She measure's one side of her living room and finds it measures 17 meters.
Area is what is on the inside.
The perimeter is the outside of the hole thing.
Hence, the length is used to measure the distance between to end points or edges.
so 17 meters measurement represent the length.
Learn more about perimeter here:
https://brainly.com/question/10466285
#SPJ5
just need the first question
Answer:
[2,3)
Step-by-step explanation:
[0,1), [0,1),[0,1),[0,1)
[1,2), [1,2),[1,2),[1,2),[1,2),[1,2),[1,2),[1,2)
[2,3),[2,3),[2,3),[2,3),[2,3),[2,3),[2,3),[2,3),[2,3),[2,3),[2,3)
[3,4),[3,4),[3,4),[3,4),[3,4),[3,4),[3,4)
If three points of a parallelogram are A (-5, -2), B (1,5), C (7.1). Which of the
following is the fourth point D of parallelogram ABCD?
(13,8)
(13.-6)
(1. -2)
(1,-6)
If the mean of a symmetric distribution is 60, which of these values could be
the median of the distribution?
A. 100
B. 60
C. 80 As
D. 30
SUBMIT
Answer:
i think ...
Step-by-step explanation:
symmetric distribution usually be a bell shape distribution .
most likely the median = mean = 60
The required value of 60 could be the median of the distribution. Option B is correct.
What is mean?The mean of the values is the ratio of the total sum of values to the number of values.
What is the median?When a dataset is ordered, the median is the value that is exactly in the middle. It is a measure of central tendency that distinguishes between the lowest and top 50% of data.
Here,
The mean of a symmetric distribution is 60.
Since for the symmetric data and rational data, the mean is equal to the median,
So Mean = Median
Median = 60
Thus, the required value of 60 could be the median of the distribution.
Learn more about mean here:
https://brainly.com/question/15397049
#SPJ2
profit 75% retail $350. what is cost at wholesale
Answer:
Step-by-step explanation:
350-75%=87.5\\so 350-87.5\\=262.5\\$262.5 dolla profit\\
The senior classes at Snellville High and General High planned separate trips to the water park. The senior class at Snellville rented and filled 12 vans and 14 buses with 796 students. General High rented and filled 14 vans and 12 buses with 738 students. How many students would fill 2 buses and 3 vans?
Answer:
133 Students
Step-by-step explanation:
Let the number of student in a van=v
Let the number of student in a bus=b
The senior class at Snellville rented and filled 12 vans and 14 buses with 796 students.
Therefore: 12v+14b=796
General High rented and filled 14 vans and 12 buses with 738 students.
Therefore: 14v+12b=738
We solve the two resulting equations simultaneously
12v+14b=796
14v+12b=738
Multiply equation 1 by 12 and equation 2 by 14 to eliminate b
144v+168b=9552
196v+168b=10332
Subtract
-52v=-780
Divide both sides by -52
v=15
We substitute v=15 to obtain b in any of the equations
12v+14b=796
12(15)+14b=796
14b=796-180
14b=616
Divide both sides by 14
b=44
Therefore a bus contains 44 Students and a Van contains 15 students.
Number of Students who would fill 2 buses and 3 vans
=2b+3v
=2(44)+3(15)
=133 Students
Write an equation of the line passing through the point A(2, 0) that is parallel to the line y = 3x−5
Answer:
y = 3x-6
Step-by-step explanation:
y = 3x−5
This is in slope intercept form
y = mx+b where m is the slope and b is the y intercept
m =3
Parallel lines have the same slope
We have the slope m=3 and a point (2,0)
y = mx+b
y = 3x+b
Substituting the point into the equation to solve for b
0 = 3(2)+b
0 = 6+b
b = -6
y = 3x-6
Answer:
y = 3x - 6
Step-by-step explanation:
Parallel lines have the same slope,
So m = 3
y - 0 = 3(x - 2)
y = 3x - 6
3A wholesaler buys baseball gloves for $15 each. He then marks up the price to $20. By what percentage was the price of the baseball glove increased
Answer:
25%
Step-by-step explanation:
−7×8=?????????????????????????
Answer
the answer is -56
Step-by-step explanation:
Write the fraction from least to greatest: 1/8, 1/3, 1/8
Answer:
Start with making them equal.
1/8 --> 3/24
1/8 --> 3/24
1/3 --> 8/24
Now order them.
1/8, 1/8, 1/3.
Hope this helps ;)
Sheila earns $8 per hour at her afterschool job. After working one week, she received a paycheck for $104. Write and solve an equation to find the number of hours Sheila worked. Fill in the blank with the solution only.
Answer:
13
Step-by-step explanation:
It should just be 104 divided by 8 which equals=13
Which category is not one of the major responsibilities of state government?
A. Economic development
B. Corrections
C. Electrical power
D. Law enforcement
Answer: C electricity
Step-by-step explanation:
It is
The MIT soccer team has 2 games scheduled for one weekend. It has a 0.4 probability of not losing the first game. and a 0.7 probability of not losing the second game, independent of the first. If it does not lose a particular game, the team is equally likely to win or tie. independent of what happens in the other game. The MIT team will receive 2 points for a win, 1 for a tie. and 0 for a loss. Find the PMF of the number of points that the team earns over the weekend.
Answer:
Step-by-step explanation:
To determine the PMF of the points that the team receive, we must determine the probabilities of winning each of the games.
Consider the firt game. We know that the probability of not losing is 0.4. Since the team can either lose the game or not, we have that the probability of losing it is 0.6. We are told that given that the team does not lose, the probability of winning or having a tie is the same. Recall that, given events A, B, the conditional probability P(A|B) (which means probability of A given B) is given as
[tex]P(A|B) = \frac{P(A\cap B)}{P(B)}[/tex]
in our case, we have that B:= not losing the game. Consider A:= To win the game, C:= To tie the game. We know that P(A|B)=P(C|B). When the team doesn't lose, then the team either ties or wins, this means that
[tex]P(A|B)+P(C|B) = 1[/tex]
So we get that P(A|B) = P(C|B) = 1/2. Let us find P(A)
[tex]P(A|B) = \frac{P(A\cap B)}{P(B)} = \frac{P(A)}{P(B)}=\frac{1}{2}[/tex]
Then [tex]P(A) = \frac{P(B)}{2} = 0.2[/tex]. By an analogous calculation we have that P(A) = P(C) = 0.2.
We will define the following events: [tex]W_i[/tex] is the event that the team wins the game i, [tex]T_i[/tex] is the event that the team ties the game i and [tex]L_i[/tex] is the event that the team loses the game i. In this notation, we have that
[tex]P(W_1) = P(T_1) = 0.2, P(L_1) = 0.6[/tex]
By reasoning the same way for the second game, we can calculate that
[tex]P(W_2)=P(T_2)=0.35, P(L_2) = 0.3[/tex]
To calculate the PMF we must check all the possible outcomes of the results of both games. Since we can either win (W), tie(T) or lose(L) a game, we will express the outcome as follows TW(3) means that the team ties the first game and wins the second one, for a total of points. In this way, the possible outcomes are
WW(4), WT(3), WL(2), TW(3), TT(2), TL(1), LW(2), LT(1), LL(0)
We see that the number of possible points are 0,1,2,3,4. Let X be the number of points, to get the pmf of X is to give the probability P(X=k) for k=0,1,2,3,4 explicitly. Note that since each game is independent of each other, to get the probability of one of the outcomes it suffices to multiply the probability of each event. For example we have that [tex]P(WW) = P(W_1)\cdotP(W_2) = 0.07[/tex]
Then, the pmf is given by
[tex]P(X=0) = P(LL) = 0.18[/tex]
[tex]P(X=1)=P(LT)+P(TL) = 0.27[/tex]
[tex]P(X=2)=P(LW)+P(TT)+P(WL) = 0.34[/tex]
[tex]P(X=3)=P(WT)+P(TW) = 0.14[/tex]
[tex]P(X=4)=P(WW)= 0.07[/tex]
.A variety of stores offer loyalty programs. Participating shoppers swipe a bar-coded tag at the register when checking out and receive discounts on certain purchases. A typical Saturday morning shopper who does not participate in this program spends $120 on her or his order. In a sample of 80 shoppers participating in the loyalty program, each shopper spent $130 on average during a recent Saturday, with standard deviation $40. Is this statistical proof that the shoppers participating in the loyalty program spent more on average than typical shoppers?a.State the null and the alternative hypotheses.b.Find the p-value of the test.
Answer:
a) Null hypothesis:[tex]\mu \leq 120[/tex]
Alternative hypothesis:[tex]\mu > 120[/tex]
b) [tex]t=\frac{130-120}{\frac{40}{\sqrt{80}}}=2.236[/tex]
The degrees of freedom are given by:
[tex] df = n-1 = 80-1=79[/tex]
The p value for this case taking in count the alternative hypothesis would be:
[tex]p_v =P(t_{79}>2.236)=0.0141[/tex]
Step-by-step explanation:
Information given
[tex]\bar X=130[/tex] represent the sample mean for the amount spent each shopper
[tex]s=40[/tex] represent the sample standard deviation
[tex]n=80[/tex] sample size
[tex]\mu_o =120[/tex] represent the value to verify
t would represent the statistic
[tex]p_v[/tex] represent the p value f
Part a
We want to verify if the shoppers participating in the loyalty program spent more on average than typical shoppers, the system of hypothesis would be:
Null hypothesis:[tex]\mu \leq 120[/tex]
Alternative hypothesis:[tex]\mu > 120[/tex]
The statistic for this case would be given by:
[tex]t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}[/tex] (1)
Replacing the info given we got:
[tex]t=\frac{130-120}{\frac{40}{\sqrt{80}}}=2.236[/tex]
The degrees of freedom are given by:
[tex] df = n-1 = 80-1=79[/tex]
The p value for this case taking in count the alternative hypothesis would be:
[tex]p_v =P(t_{79}>2.236)=0.0141[/tex]
Choose the equation that best fits the following graph.
Answer:
c. y = 3.25^x
Step-by-step explanation:
At x=1, the value of y is slightly more than 3, so the base must be more than 3. The appropriate choice is ...
y = 3.25^x
Which of the following is not a binorrial experiment?
a Asking 100 people whether or not the like pizza.
b. Measuring the height of 100 people to see if they are over 61.
Asking 100 people what their favorite color is.
d. Asking 100 people if their favorite color is red.
Answer:
You don't need experiments to ask people questions
if 8% is deducted from the bill,$384 bill remains to be paid. How much is the original bill?
Answer:
$353.28
Step-by-step explanation:
a cinema seats 280 people. if 98 people are in the cinema what percentage of seats are filled?
Answer:
35%
Step-by-step explanation:
The total number of cinema seats can seat 280 people. Since 98 people take up 98 seats of the cinema, they are taking up 98 cinema seats out of the 280 cinema seats originally available.
As a fraction this would be written as [tex]\frac{98}{280}[/tex] .
What you want to do is then divide 98 by 280 or 98/280, to get 0.35.
To get the percentage of seats filled, you must multiply the decimal you get by 100.
So it should look like this and your result should be 35%.
[tex]\frac{98}{280} = 0.35 *100=35[/tex]%
Choose the property of addition. ( 5 + 3 ) + 8 = 5 + ( 3 + ? )
A. associate property of addition
B. Commutative property of addition
C. Distributive property
D. Identity property of addition
Answer:
A. associative property of addition
Step-by-step explanation:
Associative because you can add or multiply those regardless of how the numbers are grouped.
I hope this helped and have a good rest of your day!
Answer:
Associative Property of Addition
Step-by-step explanation:
This property states that the sum of 3 or more numbers stays the same, no matter how they are grouped.
Hope this helped. Have an awesome day!
Ming throws a stone off a bridge into a river below.
The stone's height (in meters above the water), xxx seconds after Ming threw it, is modeled by:
h(x)=-5(x-1)^2+45h(x)=−5(x−1)
2
+45h, left parenthesis, x, right parenthesis, equals, minus, 5, left parenthesis, x, minus, 1, right parenthesis, squared, plus, 45
How many seconds after being thrown will the stone reach its maximum height?
Answer:
1 seconds after being thrown, the stone reaches its max height
Step-by-step explanation:
Answer:1 Seconds Is wrong the correct answer is 2
Step-by-step explanation:
Khan said so
PLEASE LIKE AND RATE IF YOU GOT YOUR QUESTION RIGHT!!!
Graph the equation y=x²-8x+7 on the accompanying set of axes. You must plot 5 points including the roots and the vertex.
Answer:
vertex is: (4,-9)
y intercept= (0,7)
roots= (1,0) and (7,0)
Step-by-step explanation:
so we can use factoring to solve this quadratic equation real quick:
x^2-7x-1x+7
x(x-7)
-1(x-7)
(x-1)(x-7)=0
x-1=0
x=1
x-7=0
x=7
(1,0) and (7,0) are the roots
axis of symmetry: 8/2=4
substitute axsis of symmetry in equation to get vertex:
4^2-8(4)+7
16-32+7
-16+7=-9
vertex is: (4,-9)
y intercept= (0,7)
roots= (1,0) and (7,0)
Hope this helps
Who’s good on algebra 1 ? Need help
Answer:
Which expression is equivalent to 3 over 175
I would say try - C or D
Hi guys, Can anyone help me with this tripple integral? Thank you:)
I don't usually do calculus on Brainly and I'm pretty rusty but this looked interesting.
We have to turn K into the limits of integration on our integrals.
Clearly 0 is the lower limit for all three of x, y and z.
Now we have to incorporate
x+y+z ≤ 1
Let's do the outer integral over x. It can go the full range from 0 to 1 without violating the constraint. So the upper limit on the outer integral is 1.
Next integral is over y. y ≤ 1-x-z. We haven't worried about z yet; we have to conservatively consider it zero here for the full range of y. So the upper limit on the middle integration is 1-x, the maximum possible value of y given x.
Similarly the inner integral goes from z=0 to z=1-x-y
We've transformed our integral into the more tractable
[tex]\displaystyle \int_0^1 \int_0^{1-x} \int _0^{1-x-y} (x^2-z^2)dz \; dy \; dx[/tex]
For the inner integral we get to treat x like a constant.
[tex]\displaystyle \int _0^{1-x-y} (x^2-z^2)dz = (x^2z - z^3/3)\bigg|_{z=0}^{z= 1-x-y}=x^2(1-x-y) - (1-x-y)^3/3[/tex]
Let's expand that as a polynomial in y for the next integration,
[tex]= y^3/3 +(x-1) y^2 + (2x+1)y -(2x^3+1)/3[/tex]
The middle integration is
[tex]\displaystyle \int_0^{1-x} ( y^3/3 +(x-1) y^2 + (2x+1)y -(2x^3+1)/3)dy[/tex]
[tex]= y^4/12 + (x-1)y^3/3+ (2x+1)y^2/2- (2x^3+1)y/3 \bigg|_{y=0}^{y=1-x} [/tex]
[tex]= (1-x)^4/12 + (x-1)(1-x)^3/3+ (2x+1)(1-x)^2/2- (2x^3+1)(1-x)/3[/tex]
Expanding, that's
[tex]=\frac{1}{12}(5 x^4 + 16 x^3 - 36 x^2 + 16 x - 1)[/tex]
so our outer integral is
[tex]\displaystyle \int_0^1 \frac{1}{12}(5 x^4 + 16 x^3 - 36 x^2 + 16 x - 1) dx[/tex]
That one's easy enough that we can skip some steps; we'll integrate and plug in x=1 at the same time for our answer (the x=0 part doesn't contribute).
[tex]= (5/5 + 16/4 - 36/3 + 16/2 - 1)/12[/tex]
[tex]=0[/tex]
That's a surprise. You might want to check it.
Answer: 0
Some shrubs have the useful ability to resprout from their roots after their tops are destroyed. Fire is a particular threat to shrubs in dry climates, as it can injure the roots as well as destroy the aboveground material. One study of resprouting took place in a dry area of Mexico. The investigation clipped the tops of samples of several species of shrubs. In some cases, they also applied a propane torch to the stumps to simulate a fire. Of 19 specimens of a particular species, 6 resprouted after fire. Estimate with 96% confidence the proportion of all shrubs of this species that will resprout after fire. Interval: .1884 to
The 96% confidence interval for the proportion of all shrubs of this species that will resprout after fire is approximately 0.1274 to 0.5042.
Here, we have,
To estimate the proportion of all shrubs of this species that will resprout after fire with 96% confidence, we will use the formula for a confidence interval for a proportion.
The formula for the confidence interval for a proportion (p) is given by:
CI = p ± Z * √(p * (1 - p) / n)
where:
CI is the confidence interval
p is the sample proportion (resprouted specimens / total specimens)
Z is the critical Z-score corresponding to the desired confidence level (96% confidence level corresponds to a Z-score of approximately 1.750)
n is the sample size (total number of specimens)
Given information:
Total number of specimens (n) = 19
Number of specimens that resprouted after fire = 6
Now, calculate the sample proportion (p):
p = (number of specimens that resprouted) / (total number of specimens)
p = 6 / 19 ≈ 0.3158 (rounded to four decimal places)
Now, calculate the critical Z-score for a 96% confidence level (use a Z-table or calculator):
Z ≈ 1.750
Now, calculate the margin of error (E):
E = Z * √(p * (1 - p) / n)
E = 1.750 * √(0.3158 * (1 - 0.3158) / 19)
E ≈ 0.1884 (rounded to four decimal places)
Finally, calculate the confidence interval:
CI = p ± E
CI = 0.3158 ± 0.1884
The 96% confidence interval for the proportion of all shrubs of this species that will resprout after fire is approximately 0.1274 to 0.5042.
To learn more on probability click:
brainly.com/question/11234923
#SPJ4
Show steps how to solve for y!!!!!
2y+2=3y/2
Please help me
[tex]\text{Solve for y:}\\\\2y+2=\frac{3y}{2}\\\\\text{Multiply both sides by 2 to cancel the denominator}\\\\4y+4=3y\\\\\text{Subtract 3y from both sides}\\\\y+4=0\\\\\text{Subtract 4 from both sides}\\\\\boxed{y=-4}[/tex]
Answer:-4
Step-by-step explanation:
2y+2=3y/2
Cross multiply
2(2y+2)=3y
Open bracket
4y+4=3y
Collect like terms
4y-3y=-4
y=-4
3.6 x 0.025 is my question to be answered
Answer:
0.09
because I multiplied...
Answer:
0.09
Step-by-step explanation:
36/ 10 x 25/ 1000 = 18/ 5 x 1/40 = 9/100 = 0.09
A movie theater has a seating capacity of 387. The theater charges $5.00 for children, $7.00 for students, and $12.00 of
adults. There are half as many adults as there are children. If the total ticket sales was $ 2808, How many children,
students, and adults attended?
Answer:
The attendance was 198 children, 90 students and 99 adults.
Step-by-step explanation:
We define:
c: children attendance
s: students attendance
a: adult attendance
The equation that describes the total ticket sales is:
[tex]5c+7s+12a=2808[/tex]
We also know that the children attendance doubles the adult attendance:
[tex]c=2a[/tex]
The third equation is the seating capacity, which we assume is full:
[tex]c+s+a=387[/tex]
We start by replacing variables in two of the equations:
[tex]c=2a\\\\s=387-c-a=387-2a-a=387-3a[/tex]
Then, we solve the remaining equation for a:
[tex]5c+7s+12a=2808\\\\5(2a)+7(387-3a)+12a=2808\\\\10a+(2709-21a)+12a=2808\\\\10a+12a-21a=2808-2709\\\\a=99[/tex]
Then, we solve for the other two equations:
[tex]c=2a=2*99=198\\\\s=387-3a=387-3*99=387-297=90[/tex]
The attendance was 198 children, 90 students and 99 adults.