The best linear equation that describe given graph is y=2.5x-35 i.e. C.
What is a linear equation ?
A linear equation is a mathematical equation that, when plotted on a graph, represents a straight line. It is an equation of the following form:
y = mx + b
where y = dependent variable, x = independent variable, m= slope of the line, and b = y-intercept (the point where the line crosses the y-axis).
Now,
Lets take a point on the given graph that is on line (50,90)
then the equation of line should give the same values.
So,
For A, y=0.4x-35
y=0.4*50-35
y=-15 Hence, It does not follow.
For B, y= y=0.4x-70
y=0.4*50-70
y=-50 Hence, It does not follow.
For C, y= y=2.5x-35
y=2.5*50-35
y=125-35
y=90
Hence, It does follow the given point.
Therefore, The best linear equation that describe given graph is y=2.5x-35
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Let f(x) = -3x - 5
What is the value of f(-5)?
Answer:
I think its 10Step-by-step explanation:
Suppose that Y1, . . . , Yn is a sample of size n from a Exp(θ), with θ > 0, E[Y1] = θ and V(Y1) = θ^2
.
a) Find the distribution of Y¯Bar and Y(1) = min(Y1, . . . , Yn).
b) Find the constants c1 and c2 such that T1 = c1Y(1) and T2 = c2Y¯Bar are unbiased the estimators of θ. Compare the MSE of T1 and T2
c) Show that Q(Y1, . . . , Yn; θ) = 2nY(1)/θ ∼ Chi-sqaure(2).
d) Construct a two-sided 1 − α confidence interval for θ using the pivot in c).
Answer:
See below.
Step-by-step explanation:
a)
Since Y1, ..., Yn are independent and identically distributed, we have Y¯Bar ~ Exp(θ/n) and Y(1) ~ Exp(nθ).
b)
We want to find c1 and c2 such that E[T1] = θ and E[T2] = θ. We have E[Y(1)] = 1/θ and E[Y¯Bar] = θ/n, so setting T1 = c1Y(1) gives E[T1] = c1/θ = θ, and setting T2 = c2Y¯Bar gives E[T2] = c2θ/n = θ. Thus, c1 = θ^2 and c2 = n. To compare the MSE of T1 and T2, we compute,
MSE(T1) = V(T1) + [E(T1) - θ]^2
= V(θY(1)) + [θ - θ]^2
= θ^2V(Y(1))
= θ^2/θ^2
= 1
MSE(T2) = V(T2) + [E(T2) - θ]^2
= V(nY¯Bar) + [θ - θ]^2
= n^2V(Y¯Bar)/n^2
= V(Y¯Bar)/n
= (θ^2/n^2)(n/θ)
= θ^2/n
Since MSE(T2) < MSE(T1) for n > 1, T2 is the preferred estimator.
c)
Let Q(Y1, ..., Yn; θ) = 2nY(1)/θ. We have E[Q] = 2n/θ and V(Q) = 4n^2V(Y(1))/θ^2 = 4n^2/θ^2. To show that Q ~ Chi-squared(2), we need to show that Q has a gamma distribution with parameters k = 2 and θ = 1/2. We have,
fQ(q) = (1/θ^k)(q^(k-1) exp(-q/θ))/Γ(k) = (1/2^2)(q/2)exp(-q/2) = (1/4)q/2 exp(-q/2)
which is the pdf of a gamma distribution with k = 2 and θ = 1/2.
d)
To construct a two-sided 1 - α confidence interval for θ, we use the fact that 2nY(1)/Q(Y1, ..., Yn; θ) ~ F(2, 2n). Let Fα/2 be the (1 - α/2) quantile of the F distribution with 2 and 2n degrees of freedom. Then we have,
P(2nY(1)/(Fα/2) < θ < 2nY(1)/(F1-α/2)) = 1 - α
So the confidence interval is [2nY(1)/(Fα/2), 2nY(1)/(F1-α/2)].
If I get paid $12.50 an hour and I worked a total of 15 hours and 35 minutes how much did I make?
Answer: $194.79
Step-by-step explanation:
It is easiest to approach this question in two parts.
First part is simple - multiply the wage per hour times the number of whole number you have worked. ($12.50)(15) = $187.50
Next you need to find how much you make in 35 minutes at a wage rate of 12.50 an hour. You can set up a ratio to find this out -
($12.50) | (60 min) - (x dollars) | (35 min)
then cross multiply and divide - (12.5 * 35) / 60 = 7.291
This means you make $7.29 for 35 minutes of work.
$187.50 + $7.29 = $194.79 for 15 hours 35 minutes of work.
(this is based on a per minute/hour scale)
Find an equation of the line that passes through the pair of points (4,5) & (-1, -1). Write the equation in the form Ax+By=C
In response to the stated question, we may state that Hence the slope equation of the line passing through the points (4, 5) and (-1, -1) in the form Ax+By=C is: 6x - 5y = -1.
what is slope?Slope is just the curvature of a bend or line in mathematics. It is a measure of the manner in which the y-value of something like a function varies because when x-value changes. The slope of a line is commonly symbolized by the letter m and may be computed as follows: m = (y2 - y1) / (x2 - x1) (x1, y1) and (x2, y2) are any 2 options on the line. A bridge's slope might be negative, negative, zero, or unknown. A positive slope indicates that the line ascends to left to right, whereas a slope indicates that the line drops from left to right.
We must use the point-slope form of the equation of a line to obtain the equation of a line of the form Ax+By=C that goes through two points:
y - y1 = m(x - x1) (x - x1)
where (x1, y1) is the location of one of the points and m is the line's slope.
Then, we must determine the slope of the line.
[tex]m = (y2 - y1) / (x2 - x1) (x2 - x1)\\where (4, 5) = (x1, y1) and (x2, y2) = (-1, -1)m = (-1 - 5) / (-1 - 4) = -6 / (-5) = 6/5\\y - y1 = m(x - x1) (x - x1)\\y - 5 = (6/5)(x - 4) (x - 4)\\5y - 25 = 6x - 24\\6x - 5y = -1\\[/tex]
Hence the equation of the line passing through the points (4, 5) and (-1, -1) in the form Ax+By=C is: 6x - 5y = -1.
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What is 1/2 + p = -3 ?
Answer:
p= -3-1/2
p= -7/2
Step-by-step explanation:
(you transpose the fraction /take the liketerms)
( you transpose your fraction will change the sign and become negative then -3-0.5or -3-1/2=-7/2.)then you substitute to the original equation 1/2+p=-3 check your answer .
In ΔIJK, i = 100 inches, mm∠I=115° and mm∠J=23°. Find the length of j, to the nearest inch.
The measure of the side J of the triangle ΔIJK will be 43 units.
What is the law of sine?The law of sines defines the ratio of triangle sides, and their respective sine angles are equivalent. The law of sines is also known as the sine law, sine rule, and sine formula.
Given that in the triangle i = 100 inches, m∠I=115° and m∠J=23°. The measure of the length J will be calculated as:-
100 / sin115 = J / sin23
J = (100) x sin23 / sin115
J = 100 x 0.43
J = 43 units
The length of side J will be 43 units.
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Brendon is building a clubhouse where 1 inch on the plans is equivalent to 8 inches on the actual clubhouse.
If the clubhouse is to be 126 inches wide, what will the width be on the plans?
Round answer to the nearest hundredth if necessary.
Answer:
To find the width of the clubhouse on the plans, we need to use the given scale of 1 inch on the plans being equivalent to 8 inches on the actual clubhouse. Let's assume that "x" inches on the plan correspond to the actual width of 126 inches of the clubhouse.
Using the proportionality of the scale, we can set up the following equation:
1 inch / 8 inches = x inches / 126 inches
Simplifying the equation, we can cross-multiply to get:
8 inches * x inches = 1 inch * 126 inches
8x = 126
x = 15.75
Therefore, the width of the clubhouse on the plans is 15.75 inches.
I'LL MARK THE BRAINLIEST
In this figure, 14.2% of the area is painted green. How much of the area is painted green?
Answer:
8.449 square centimeters
Step-by-step explanation:
Area of the figure = area of square + area of triangle
[tex] {7}^{2} + \frac{1}{2} (3)(7) = 49 + 10.5 = 59.5[/tex]
[tex].142 \times 59.5 = 8.449[/tex]
So 8.449 square centimeters of this figure is green.
What is m24 if m25 = (2x)° and m24 = (x +9)°?
4
X
5
m24 =
The value of angle m<4 is 66 degrees
What are supplementary angles?The angles on a straight line are supplementary, this means that the angles sum up to 180 degrees.
From the information given, we have that;
m<4 = x + 9 degreesm< 5 = 2x degreesEquate the angles to 180 degrees
We have;
m<4 + m<5 = 180
Substitute the expression for each of the angles , we have;
x + 9 + 2x = 180
collect the like terms
3x = 180 - 9
subtract the values
3x = 171
Divide by the coefficient
x = 57
But m<4 = 57 + 9 = 66 degrees
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The table shows the results for spinning the spinner 75 times. What is the relative frequency for the event "spin a 4"?The table shows the results for spinning the spinner 75 times. What is the relative frequency for the event "spin a 4"?
Answer:
Answer: 6/25
======================================================
Explanation:
The table shows the spinner lands on "4" exactly 12 times out of the 50 total.
12/50 = (2*6)/(2*25) = 6/25
In decimal form that is 6/25 = 0.24 which converts to 24%
A primary credit card holder's card has an APR of 11.99%. The current monthly balance, before interest, is $7,568.19. The cardholder makes a payment of $350 the first 11 months and then pays off the balance at the end of the 12th month. How much interest did the credit card holder pay?
$720.27
$156.34
$370.31
$679.70
The credit card holder paid $720.27 in interest over the 12 months. Answer choice A, $720.27, is the correct answer.
What is simple interest?
Simple Interest (S.I.) is the method of calculating the interest amount for a particular principal amount of money at some rate of interest.
First, let's calculate the monthly interest rate by dividing the APR by 12:
11.99% / 12 = 0.99917%
Next, let's calculate the interest paid on the monthly balance for each of the 11 months before the final payment:
Month 1:
Interest = $7,568.19 x 0.99917% = $75.59
Month 2:
Balance = $7,568.19 - $350 - $75.59 = $7,142.60
Interest = $7,142.60 x 0.99917% = $71.38
Month 3:
Balance = $7,142.60 - $350 - $71.38 = $6,721.82
Interest = $6,721.82 x 0.99917% = $67.11
Month 4-11: (follow the same process as above)
Interest for Month 4: $63.82
Interest for Month 5: $60.51
Interest for Month 6: $57.17
Interest for Month 7: $53.80
Interest for Month 8: $50.41
Interest for Month 9: $47.00
Interest for Month 10: $43.56
Interest for Month 11: $40.11
Now, at the end of month 11, the cardholder has a balance of:
$7,568.19 - ($350 x 11) - $75.59 - $71.38 - $67.11 - $63.82 - $60.51 - $57.17 - $53.80 - $50.41 - $47.00 - $43.56 - $40.11 = $1,225.74
Finally, the cardholder pays off the remaining balance of $1,225.74 at the end of month 12. The interest charged for this month would be:
Interest = $1,225.74 x 0.99917% = $12.25
So the total interest paid by the cardholder over the 12 months is:
$75.59 + $71.38 + $67.11 + $63.82 + $60.51 + $57.17 + $53.80 + $50.41 + $47.00 + $43.56 + $40.11 + $12.25 = $720.27
Therefore, the credit card holder paid $720.27 in interest over the 12 months. Answer choice A, $720.27, is the correct answer.
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Triple the sum of K and 2
"Triple the sum of K and 2" can be interpreted as a two-step procedure that involves adding K and 2 first, and then multiplying the result by 3.
What is multiplication?Multiplication is a fundamental arithmetic operation that involves combining two or more numbers to find their product. It is represented by the symbol "x" or "•" or sometimes simply by placing two numbers next to each other.
According to question:"Triple the sum of K and 2" can be expressed mathematically as:
3(K + 2)
This expression represents the value we get by adding K and 2, and then multiplying the sum by 3.
To evaluate this expression, we first add K and 2 together, giving us a sum of (K + 2). Then, we multiply that sum by 3, giving us a final result of 3(K + 2).
As a result, "triple the sum of K and 2" can be interpreted as a two-step procedure that involves adding K and 2 first, and then multiplying the result by 3.
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The full question is How do you write "triple the sum of K and 2" as an expression?
(x^2-4x+3) + (3x^2-3x-5) ASAP PLS
Answer:
(x - 2)(4x + 1)
-16=(-4)-6x what does x mean
Answer: x=2 is the answer
Answer:
Step-by-step explanation
Rearrange terms
-16=(- 4)- 6 x
-16=-6x - 4
Add 4 to both sides
-16= - 6x - 4
-16 + 4= -6x - 4 + 4
Simplify the expression
-16+4=6x - 4+4
-12=6x
Divide both sides by the same factor
-12=6x
-12/-6= -6x/-6
so
x=2
Math
Practice solving.
1. What is the sum of -5/7 and 3/7?
2. Find the different of 5/12 - 3/4
3. Find the difference of 1/8 - 13/2
4. Find the sim of 2/3 and 1/3
5. Find the difference of 3/4 and 1/3
6. What is 3/5 x 4/6
7. What is -8/9 x 3/4
8. What is 2 2/3 x 4/5
9. What is 3/4 of 120
10. What is 2/3 of 360
11. What is 1/3 of 180
12. Multiply 16/24 by 8/20
13. Multiply 1/7 by 4/1
14. What is 1/5 x 8/1
15. Multiply 4/7 x 6/1
16. Divide 3/8 and 2/5
17. Divide 16/21 and 24/14
18. What is 4/5 divided by 7/10
19. What is -4/15 divided by 8/12
20. What is 4/6 divided by -8
Answer:
1. -2/7
2. 7/6
3. 53/8
4. do u mean sum? if yes then the answer is 1
5. 5/12
6. 2/5
7. -2/3
8.
9.90
10.240
11.60
12. 4/15
13.4/7
14.8/5
15.24/7
16.15/16
17.4/9
18.8/7
19.-2/5
20.-1/12
How many solutions and what is the solution, as an ordered pair?
Hence, there is only one answer, which is (-3, 3) as the two lines intersect in order to obtain the solution(s) to the system of equations.
what is solution ?A value or combination of values that satisfy an equation, inequality, system of equations, or system of inequalities are known as solutions in mathematics. Take the equation x2 - 3x + 2 = 0, for instance. This equation has a solution in the form of an x value that makes the equation true. The quadratic formula allows us to determine that this equation has two solutions, x = 1 and x = 2. According to this, a solution for a system of equations is a set of values that simultaneously satisfy every equation in the system. Mathematical problem-solving, which has many applications in areas like engineering, physics, economics, and more, is a crucial component of the subject.
given
We must identify the point(s) at where the two lines intersect in order to obtain the solution(s) to the system of equations depicted by the graph. The graph demonstrates that the lines cross at the location (-3, 3).
Hence, there is only one answer, which is (-3, 3) as the two lines intersect in order to obtain the solution(s) to the system of equations.
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PLEASE HELP ME SOLVE THIS PROBLEM!!
Answer:
mm eh its too hard im onwy one!
Step-by-step explanation:
A normal population has a mean of $76 and standard deviation of $6. You select random samples of 40.
1. What is the probability that a sample mean is less than $75? (Round z-value to 2 decimal places and final answer to 4 decimal places.)
2. What is the probability that a sample mean is between $75 and $77? (Round z-value to 2 decimal places and final answer to 4 decimal places.)
3. What is the probability that a sample mean is between $77 and $78? (Round z-value to 2 decimal places and final answer to 4 decimal places.)
4. What is the probability that the sampling error ( x¯
− μ) would be $1.50 or less? (Round z-value to 2 decimal places and final answer to 4 decimal places.)
Using a z-table, the probability of a z-score less than 1.58 is 0.9429 (rounded to 4 decimal places).
What is probability?Probability is a measure of the likelihood or chance of an event occurring. It is expressed as a number between 0 and 1, where 0 represents an impossible event and 1 represents a certain event. The probability of an event can be calculated by dividing the number of favorable outcomes by the total number of possible outcomes. It is used in various fields such as mathematics, statistics, science, and finance to make predictions and analyze data.
Here,
1. The z-score for a sample mean of $75 is calculated as:
z = (75 - 76) / (6 / √(40)) = -2.36
Using a z-table, the probability of a z-score less than -2.36 is 0.0099 (rounded to 4 decimal places).
2. The z-score for a sample mean of $75 is calculated as:
z1 = (75 - 76) / (6 / √(40))
= -2.36
The z-score for a sample mean of $77 is calculated as:
z2 = (77 - 76) / (6 / √(40))
= 0.79
Using a z-table, the probability of a z-score between -2.36 and 0.79 is 0.8669 (rounded to 4 decimal places).
3. The z-score for a sample mean of $77 is calculated as:
z1 = (77 - 76) / (6 / √(40))
= 0.79
The z-score for a sample mean of $78 is calculated as:
z2 = (78 - 76) / (6 / √(40))
= 1.57
Using a z-table, the probability of a z-score between 0.79 and 1.57 is 0.0823 (rounded to 4 decimal places).
4. The standard error of the mean (SEM) is calculated as:
SEM = standard deviation / sqrt(sample size)
SEM = 6 / √(40) = 0.9487
The z-score for a sampling error of $1.50 is calculated as:
z = 1.50 / 0.9487 = 1.58
Using a z-table, the probability of a z-score less than 1.58 is 0.9429 (rounded to 4 decimal places).
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Decide if each statement is true or false and explain.
All rectangles are quadrilaterals.
Answer: True
Step-by-step explanation:
They have four sides
Answer:true.
Step-by-step explanation: All Rectangles are indeed quadrilaterals because all rectangles have 4 sides and quadrilaterals are known as a four sided shape,
What is the ordered pair that represents the point (-8, 7) after a reflection over the y-axis?
A. (-8, -7)
B. (8,7)
C. (-7,8)
(7,-8) D.
The ratio of new car sales to used car sales at the car lot is 3:5. If the total car sales were $287,400 last month, what was the total of the used car sales?
Answer:
Therefore, the total used car sales were $179,625.
Step-by-step explanation:
Let's assume that the ratio of new car sales to used car sales is 3x:5x, where x is a constant.
The total car sales were $287,400, which means the sum of the new car sales and used car sales is $287,400:
3x + 5x = 8x
So, the total sales can be expressed as:
8x = $287,400
To find the value of x, we need to divide both sides by 8:
x = $35,925
Now, we can calculate the used car sales by multiplying 5x by the value of x:
Used car sales = 5x * x = 5 * $35,925 = $179,625
Therefore, the total used car sales were $179,625.
Pupils in a class were asked how they travel to school. The results were recorded in the table below
Car 13 bus 6 train 5 walk 8
If s pupil in the class was picked at random what is the probability that one of them walked to school as a percentage
Answer:
1/3
Step-by-step explanation:
PLEASE HELP ME
Given the following quadratic functions, complete the following:
1. Identify the zeros.
2. Identify the vertex.
3. Write the quadratic equation in factored form for the function that is graphed.
The zeros and vertex of each quadratic equation are:
Case 1: y = 4 · (x + 2) · (x - 2), Roots: - 2, 2, Vertex: (0, - 16)
Case 2: y = (1 / 2) · (x + 5) · (x - 3), Roots: - 5, 3, Vertex: (- 1, - 8)
Case 3: y = - 2 · (x + 4) · (x + 2), Roots: - 4, - 2, Vertex: (- 3, 2)
Case 4: y = - 2 · (x + 6) · (x + 2), Roots: - 6, - 2
Vertex: (- 4, 8)
How to analyze quadratic functions and derive their expressions
Graphically speaking, quadratic functions have the form of the parabola. The zeros are the points of parabola that are on the horizontal axis (x-axis) and the vertex is the only point of the parabola. The factor form of the parabola is:
y = C · (x - r₁) · (x - r₂)
Where:
C - Vertex constantr₁, r₂ - RootsNow we proceed to determine all the features of the quadratic function:
Case 1
Roots: r₁ = - 2, r₂ = 2
Vertex: (h, k) = (0, - 16)
C = y / [(x - r₁) · (x - r₂)]
C = - 16 / [2 · (- 2)]
C = - 16 / (- 4)
C = 4
Factor form: y = 4 · (x + 2) · (x - 2)
Case 2
Roots: r₁ = - 5, r₂ = 3
Vertex: (h, k) = (- 1, - 8)
C = y / [(x - r₁) · (x - r₂)]
C = - 8 / [(- 1 + 5) · (- 1 - 3)]
C = - 8 / [4 · (- 4)]
C = - 8 / (- 16)
C = 1 / 2
Factor form: y = (1 / 2) · (x + 5) · (x - 3)
Case 3
Roots: r₁ = - 4, r₂ = - 2
Vertex: (h, k) = (- 3, 2)
C = y / [(x - r₁) · (x - r₂)]
C = 2 / [(- 3 + 4) · (- 3 + 2)]
C = 2 / [1 · (- 1)]
C = - 2
Factor form: y = - 2 · (x + 4) · (x + 2)
Case 4
Roots: r₁ = - 6, r₂ = - 2
Vertex: (h, k) = (- 4, 8)
C = y / [(x - r₁) · (x - r₂)]
C = 8 / [(- 4 + 6) · (- 4 + 2)]
C = 8 / [2 · (- 2)]
C = 8 / (- 4)
C = - 2
Factor form: y = - 2 · (x + 6) · (x + 2)
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19 less than a number is 28
Answer: 47
Step-by-step explanation:
28+19=47
47-19=28
To amend a country’s constitution, 7/9 of the 84 states in that country must approve the amendment. If 66 states approve the amendment, will the constitution be amended?
Answer:
Since only 66 states approve the amendment, it falls short of the required 7/9 majority. Therefore, the constitution will not be amended.
Step-by-step explanation:
To determine whether the constitution will be amended, we need to compare the number of states that have approved the amendment to the required number of states needed for approval.
The requirement is that 7/9 of the 84 states must approve the amendment. So, we need to calculate 7/9 of 84 to find out how many states need to approve the amendment:
(7/9) x 84 = 66.67
Rounding up, we see that 66.67 is equivalent to 67 states. This means that in order for the amendment to be approved, at least 67 states must approve it.
Since only 66 states approve the amendment, it falls short of the required 7/9 majority. Therefore, the constitution will not be amended.
8 books cost 19.60 which equation would help determine the cost of 10 books?
Answer: $24.5
Step-by-step explanation:
8 Books = $19.60
1 Book = $19.60/8 = $2.45
10 Books = $2.45 X 10 = $24.5
Answer:
E none of the above
Step-by-step explanation:
a correct equation would be:
8/19.60 = 10/x
or
19.60/8 = x/10
HELP! triangle JKL is similar to triangle MNO. Find OM. round your answer to the nearest tenth if necessary
The length of OM, given that the triangles are similar to each other, is calculated as: 14.4.
What are Similar Triangles?Similar triangles are triangles that have the same shape but may have different sizes. They have the same angles, but the lengths of their sides are proportional. This means that corresponding sides of similar triangles are in proportion, and the ratio of their corresponding sides is constant.
Since triangle JKL is similar to triangle MNO, therefore:
JK/MN = JL/MO
Substitute:
5/24 = 3/x
Cross multiply:
5x = 72
5x/5 = 72/5
x = 14.4
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The entry fee to East Egg Hunt Event is $7.00. Each ride requires a ticket that cost $2.00. Cassie spent a total of $45.00. How many tickets Cassie Purchase?
Answer: 19 tickets
Step-by-step explanation: $45 - $7 = 38 38 divided by $2 = 19 tickets
2 2/5 as an improper fraction in simplest form
Answer: 12/5
Step-by-step explanation:
A warehouse contains 55 boxes. Then a truck delivers a number of boxes at 12:00 p.m. and a team of workers immediately begins to unload the boxes at a constant rate. At 3:30 p.m., the warehouse contains 90 boxes. How many boxes are in the warehouse when the truck is finally empty at 8:30 p.m.?
Answer:
Let's call the number of boxes delivered by the truck x. We know that the warehouse initially contains 55 boxes, and the truck delivers x boxes, so the total number of boxes in the warehouse after the delivery is 55 + x.
We also know that the workers unload the boxes at a constant rate, which we can express as a number of boxes per hour. Let's call this rate r. Since the workers unload boxes for 3.5 hours (from 12:00 p.m. to 3:30 p.m.), we can express the number of boxes unloaded as:
Number of boxes unloaded = r * 3.5
Therefore, the total number of boxes in the warehouse at 3:30 p.m. is:
55 + x - r * 3.5
We're told that this number is 90, so we can write the equation:
55 + x - r * 3.5 = 90
Simplifying this equation, we get:
x - r * 3.5 = 35
We're also told that the truck is empty at 8:30 p.m., which means that all the boxes it delivered have been unloaded by then. So the total number of boxes in the warehouse at 8:30 p.m. is:
55 + (x - r * 8)
where 8 is the number of hours between 12:00 p.m. and 8:00 p.m.
We can use the equation x - r * 3.5 = 35 to solve for x in terms of r:
x = 35 + r * 3.5
Substituting this into the equation for the total number of boxes at 8:30 p.m., we get:
55 + (35 + r * 3.5 - r * 8)
Simplifying this expression, we get:
55 - 35 + 28r
= 20 + 28r
Therefore, the warehouse contains 20 + 28r boxes at 8:30 p.m.