A pool with a square bottom is to have a volume of 2000 cubic feet. The owners plan to use a fancy tile to complete the pool. The sides of the pool will cost $80 per square foot and the bottom of the pool will cost $40 per square foot. Find the pool dimensions that will minimize the cost of construction.

Answers

Answer 1

The pool dimensions that will minimize the cost of construction are length of square bottom = 20 ft and height of pool = 5 ft

Let l be the length of side of the square bottom of the pool and h be the height of the pool.

Its volume V = l²h

Now, the total surface area of the pool equal the area of its sides plus the area of its base.

The area of its 4 sides is 4lh.

Since the cost of the side of the pool is $80 per square foot, the total cost for the sides of the pool is C = $80 × 4lh = $ 320lh

Also, The area of its square bottom is l².

Since the cost of the side of the pool is $40 per square foot, the total cost for the square bottom of the pool is C' = $40 × l² = $ 40l²

So, the total cost of the pool is C" = C + C' = 320lh + 40l²

C" = 320lh + 40l²

Since the volume equals 2000 ft³, V = l²h

2000 = l²h

h = 2000/l²

Substituting h into C", we have

C" = 320lh + 40l²

C" = 320l × 2000/l² + 40l²

C" = 640000/l + 40l²

To find the value of l which makes C" minimum, we differentiate C" with respect to l and equate it to zero.

So, dC"/dl = d(640000/l + 40l²)/dl

dC"/dl = d(640000/l)/dl + d(40l²)/dl

dC"/dl = -640000/l² + 80l

Equating dC"/dl to zero, we have

-640000/l² + 80l = 0

-640000/l² = -80l

Cross-multiplying, we have

640000 = 80l³

Dividing through by 80, we have

l³ = 640000/80

l³ = 8000

Taking cube root of both sides, we have

l = ∛8000

l = 20 ft

We differentiate C" twice to determine if this value of l gives a minimum for C".

So, d²C"/dl² = d(-640000/l² + 80l)/dl

d²C"/dl² = d(-640000/l²)/dl + d(80l)/dl

d²C"/dl² = 640000/l³ + 80

Substituting l = 20, we have

d²C"/dl² = 640000/l³ + 80

d²C"/dl² = 640000/20³ + 80

d²C"/dl² = 640000/8000 + 80

d²C"/dl² = 80 + 80

d²C"/dl² = 160 > 0

Since d²C"/dl² = 160 > 0. So, l = 20 ft gives a minimum for C".

Since h = 2000/l²

Substituting l = 20 into the equation, we have

h = 2000/l²

h = 2000/20²

h = 2000/400

h = 5 ft

So, the pool dimensions that will minimize the cost of construction are length of square bottom = 20 ft and height of pool = 5 ft

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Related Questions

What are the x and y -intercepts for the equation 5x - 4y = 10

Answers

Answer:

x=2

y= -2.5

Step-by-step explanation:

x int

1.) set y to 0 (5x -4(0)=10

solve for 5x=10

y int

1.) set x to 0

solve for -4y=10

Answer:

x=2, y=-5/2

Step-by-step explanation:

to find the 'x' intercept, set the 'y' value to zero and solve:

5x - 4(0) = 10

5x = 10

x = 2

to find the 'y' intercept, set the 'x' value to zero and solve:

x(0) - 4y = 10

-4y = 10

y = -10/4 or -5/2

The base of the following pyramid is a square. If the volume of
the pyramid is 360 feet^3, what is the missing length? Round the
answer to the nearest hundredth.

Answers

Answer:

h = 12.52 ft

Step-by-step explanation:

volume of pyramid is 1/3*b*l. b is the base and l is the height we know that this equals 360 because it is given in the text. we also know b=8^2 since the base is a square so b=64. divide 360 by 1/3*64*pi to get l, l=5.3715. next we will use the pythagorean theorem to find h. first find the diagonal of the base: 8sqrt(2), now using the pythagorean theorem, we have h^2=5.3715^2 + (8sqrt(2))^2= 28.8528+128=156.8528. square root to get12.5241

The length and breadth of a rectangle are (2x + 1) cm
and (x + 3) cm, respectively. If the area of the
rectangle is 88 cm^2 ,find:
a. the value of x
b. the perimeter of the rectangle.

Answers

Answer:

Step-by-step explanation:

Area = 88 sq.cm

length * width = 88

(2x + 1)(x + 3)  = 88

2x*(x +3) + 1*(x + 3) = 88

2x*x + 2x*3 + x + 3= 88

2x² + 6x + x + 3 = 88

2x² + 7x + 3 - 88 = 0

2x² + 7x - 85 = 0

2x² - 10x + 17x - 85 = 0

2x(x - 5) + 17(x - 5) =0

(x - 5)(2x + 17 )= 0

x - 5 = 0      {Ignore 2x +17 = 0 as it gives a negative value}

x = 5

b) length = 2x + 1 = 2*5 + 1 = 10 +1 = 11 cm

breadth = x+ 3 = 5 + 3 = 8 cm

Perimeter = 2*(length +breadth}

                = 2* (11 + 8)

                = 2 * 19

               = 38 cm

Pleaseee helpppp me!!!!!!!!!!!!! ​

Answers

Answer:

The graph is linear and increasing from x = -6 to x = -2.

The graph is nonlinear and decreasing from x = -2 to x = 0.

Step-by-step explanation:

Linear means it has a constant slope, or a constant rate of change. That makes a straight line on a graph. On the given graph, you can see the straight line increasing from x = -6 to x = -2.

Non-linear is just anything that isn't a constant slope, and makes a curve on a graph. On the given graph, the curve decreases from x = -2 until x = 0, where it reaches its lowest point and starts heading upwards again.

find the measure of angle 1 and angle 2. justify your answer

Answers

Answer:

∠ 1 = 95° , ∠ 2 = 130°

Step-by-step explanation:

∠ 1 = 95° ( alternate angles )

∠ 2 and 50° are same- side interior angles and sum to 180°

∠ 2 + 50° = 180° ( subtract 50° from both sides )

∠ 2 = 130° ( same- side interior angle )

the sum of two rational numbers is 17/18 If one of the numbers is 5/24 find the other number

Answers

Step-by-step explanation:

x + y = 17/18

x = 5/24

5/24 + y = 17/18

to bring both fractions to the same denominator (I see it is 72, but let's do it formally correct for you to learn), we look for the LCM, the lowest common multiple of both.

for this we split both numbers into their prime factors and then build the the combination of the longest chains per prime factor :

24 = 2×2×2×3

18 = 2×3×3

the LCM (and the new denominator) is then

2×2×2×3×3 = 8×9 = 72

so,

15/72 + y = 68/72

y = 53/72

53 is a prime number, so the fraction cannot be further refined.

Choose the steeper line.


y=-6x+1

or
y=-3x-2

Answers

Answer: y=-3x-2

Step-by-step explanation:

Slope is rise over run. The slope of y=-3x-2 is -3, which is 1 down/up and 3 to the right/left. The slope of y=-6x+1 is -6 which is 1 down/ up and 6 to the right/left. When the graph is going 3 steps to the right/left, it is steeper than when its going 6 steps to the right/left.

a%b when a=2 and b=1/2

Answers

Answer:

0.01

Step-by-step explanation:

If two figures are similar, what can you say about them? Be specific and give at least 3 details.

Answers

Answer:

im confused as to if these terms are supposed to be specific or if you are looking for certain ones

Step-by-step explanation:

but i would say congruent, corresponding angles, and equal

Solve the proportion for v.
6
0]>
9 =
100
V
v = [?]

Answers

Answer:

v = 12

Step-by-step explanation:

[tex]\frac{9}{v}[/tex] = [tex]\frac{6}{8}[/tex] ( cross-  multiply )

6v = 8 × 9 = 72 ( divide both sides by 6 )

v = 12

Answer:

v=12

9/v =6/8 (cross - multiply)

6v = 8 x 9 = 72 (divide both sides by 6)

v = 12

Step-by-step explanation:

that's my answer

The formula for the area of a rhombus with diagonals of lengths c and d is A= 1/2 cd.
a. Solve the formula for c.

b. The area of a rhombus is 35 square feet. The length of one of the diagonals is 10 feet. What is the length of the other diagonal?

c. In a square (which is a rhombus), the lengths of the diagonals are the same. If a square has an area of 32 square feet, then what is the length of each diagonal

Answers

Answer:

I think it's A

Step-by-step explanation:

i apologize if I'm wrong

5x - 14 = 3(3x + 6) + 5

Answers

Answer:

x= -9.25

Step-by-step explanation:

5x - 14 = 3(3x + 6) + 5

5x - 14 = 9x + 18 + 5.......distribute

-4x = 37.............move values and combine like terms

x= -9.25.............divide both sides by -4

Barbara wants to buy muffins. Which is the best deal? O a. 9 muffins for $7.92 O b. 4 muffins for $3.60 O c. 6 muffins for $5.34 O d. 8 muffins for $7.60 N​

Answers

Answer:

D

Step-by-step explanation:

Hope it can help you lovelots

#LEARN WITH BRAINLY

In a class of 20 students, 5 have a brother and 11 have a sister. There are 3 students who have a brother and a sister. What is the probability that a student who does not have a brother has a sister?

Answers

The probability that a student who does not have a brother has a sister is 53.33%.

Probability

Given that in a class of 20 students, 5 have a brother and 11 have a sister, and there are 3 students who have a brother and a sister, to determine what is the probability that a student who does not have a brother has a sister the following calculation must be performed:

20 - 5 = 10011 - 3 = X15 = 1008 = X8 x 100 / 15 = X800 / 15 = X53.33 = X

Therefore, the probability that a student who does not have a brother has a sister is 53.33%.

Learn more about probability in https://brainly.com/question/13553988

The coordinates of which point are (–3, –6)?point Apoint Bpoint Cpoint D

Answers

The coordinates of which point are (–3, –6) is point B

What are coordinates?

Coordinates are the position of a point in the coordinate plane.

From the graph, we have the following highlights

Point B is at x = -3, and y = -6

The above means that:

(x,y) = (-3,-6)

Hence, the coordinate of (-3,-6) is point B

Read more about coordinates at:

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Answer:

its point b edge 2022

Step-by-step explanation:

plz help!

1. (0, y) , (2, 7); m = 1/2

y = _____

2. (4, 2) , (5, y) m = 4

y = _____

Answers

Answer:

Step-by-step explanation:

y = mx + b, where m is the slope and y the y-intercept (the value of y when x=0).

(0, y) , (2, 7); m = 1/2

We can start with y = (1/2)x + b

To find b, use one of the two given points.  I'll use (2,7), since (0,y) isn't helpful.

y = (1/2)x + b

7 = (1/2)*2 + b

7 = 1 + b

b = 6

The equation is y = (1/2)x + 6.

Now find (0,y) by using x = 0:

y = 6

The second point is (0,6)

============  

2. (4, 2) , (5, y) m = 4

y = mx + b

y = 4x + b

Use (4,2) and solve for b:

2 = 4*4 + b

b = -14

The equation is y = 4x - 14

Now find (5,y):

y = 4x - 14

y = 4*5 - 14

y = 20 - 14

y = 6

The second point is (5,6)

Se attached graph.

--

how to work out 85% of a number

Answers

Answer:

you change the percent into a decimal and multiply because of means multiply

Step-by-step explanation:

lets say you finding 85% of 4

.85 x 4

What is the slope of the line that passes through the points (8, 2) and (9,3)? Write
your answer in simplest form.

Answers

Answer:

Well to calculate slope you just do

y2-y1/ X2-x1

In this case

9-8/3-2

Which is 1/1

THe slope is 1

Answer:

1

Step-by-step explanation:

The slope is going to be the ratio between the difference of y coordinates, and the difference in x coordinates.

[tex]m= \frac{\Delta y}{\Delta x} = \frac{3-2}{9-8} = \frac11 = 1[/tex]

Find the value of x in each case

Answers

Answer:

Step-by-step explanation:

∠AEB + ∠FEC = 180   {linear pair}

∠AEB = 180 - 4x

DE // AB , AE is transversal,

∠EAB = ∠DEA   {Alternate interior angles}

∠EAB = 2x

∠EBC = ∠AEB + ∠EAB  {Exterior angle property}

    6x  =  180 - 4x + 2x

    6x = 180 - 2x

Add 2x to both sides

6x + 2x = 180

8x = 180

x = 180/8

x = 22.5

!!!WILL MARK BRAINLIEST IF ALL ARE ANWSERED!!! please provide short explanations

Answers

Answer:

20= 20

21. 10

22. 1.8

23. 4.4

24. 32

25. 7/9

If a=6, b=12,and c=4, then what does 2ab-c^2 equal?

Answer: 2(6)(12)-4^2 = 128

What is the prime factorization of 100,000?

Answer: 2^5× 5^5

Solve for x. 5.8 = 4x+0.2

Answer: x= 1.4

Find the area of this shape.

Answer: Area = 1.21

What is the lateral surface area of this rectangular prism?

Answer: 208 in^2

5/9 + 1/3 × 1/3 = 0.66666666666 = 2/3

Step-by-step explanation:

The prime factorization of 100,000 is 2^5 × 5^5. Since it has a total of 10 prime factors, 100,000 is a composite number.

-----------------------------------------------------------------------------------------------------

5.8-0.2=4+0.2−0.2

5.6 = 4x

5.6/4  = 4x/4

x= 1.4

-----------------------------------------------------------------------------------------------------

Square sides are equal..

A=a^2=1.1^2≈1.21

-----------------------------------------------------------------------------------------------------

The lateral surface area of a rectangular prism can be calculated by finding the sum of all the lateral faces of the prism, i.e. the total area excluding the area of the bases. The formula to find the surface area of a rectangular prism is given as, Lateral surface area of a rectangular prism = 2(l + b) h square units.

When a prism has its bases facing up and down, the lateral area is the area of the vertical faces. (For a rectangular prism, any pair of opposite faces can be bases.) The lateral area of a right prism can be calculated by multiplying the perimeter of the base by the height of the prism.

-----------------------------------------------------------------------------------------------------

Solve the equation-10 +1 +7x =37

Answers

Answer:

Answer in Explanation

Step-by-step explanation:

-10 + 1 + 7x = 37

-9 + 7x = 37

Add 9 on both sides to leave 7x alone

7x = 46

Divide by 7 to leave x alone

x = 46/7 or 6.57

If the equation is positive 10 at the beginning instead of -10 then this is the answer for that:

10 + 1 + 7x = 37

11 + 7x = 37

Subtract 11 from both sides to leave 7x alone

7x = 26

Divide by 7 to leave x alone

x = 26/7 or 3.7

HELP ME I GOT 67 POINTS THAT I WILL GIVE AND ILL GIVE YOU BRAINIST

Answers

Answer:

35.325 in³

Step-by-step explanation:

Since the base of a cylinder is a circle,

area of cylinder= πr²h

Radius, r

= diameter ÷2

= 3 ÷2

= 1.5 inches

Volume of can

= 3.14(1.5)²(5)

= 35.325 in³

35.34
V=3.14x r^2= 35.34292

answer this question!.

Answers

Answer:

  ∠A = 44°

Step-by-step explanation:

Let b represent the measure of the exterior angle at B. Let c represent the measure of the exterior angle at C. The sum of angles in the lower triangle is ...

  b/2 +c/2 +68° = 180°

  b +c = 360° -136° . . . . . multiply by 2, subtract 136°

  b +c = 224°

__

The exterior angle b is the supplement of the interior angle there, so the interior angle B is ...

  B = 180° -b

The exterior angle c is the sum of the remote interior angles, so we have ...

  c = B +A

  c = (180° -b) +A

  A = (b +c) -180° . . . . . . . . add b-180° to both sides

  A = 224° -180° = 44° . . . . substitute for (b+c)

The measure of angle A is 44°.

_____

Additional comment

The angle naming is perhaps a little unconventional, but we wanted to use names that made the answer less cumbersome to write. We consider the angle A, B, C to be the interior angles of ΔABC, and we have named the exterior angles at B and C as 'b' and 'c'.

Conventionally, 'b' and 'c' would name the sides opposite angles B and C, respectively. We're not concerned with side lengths here, so we used those letters for an unconventional purpose.

help me please!!!!!! 20 points!

Answers

Answer:

Step-by-step explanation:

2x = x + 40

2x - x = x - x + 40

x = 40

∠I = ∠Q = 33°

∠H = ∠P = 80°

∠J = ∠R = 67°

Compared to last year, the population has increased 25%. The population is now 6,600. What was the population last year?

What number of population do I put for each for percentage?

Answers

Answer:

4,950

Step-by-step explanation:

:)

1,650-25% 3,300-50% 4,950-75% 5,280-100%

Step-by-step explanation:

convert the percentage to a decimal then multiply by 6,600. To get the number of people of 100%, divide 1.25 (the percent of 6,600) by 6,600. That should be right,

Is that the right answe plzzz help me

Answers

Answer:

Your answer is All of the Above.

Hope this helps!

Step-by-step explanation:

OA is the radius

OC is the radius

and OB is the radius

( They are all half length of the circle )

how many years in two scores?brainliest best answer.

Answers

Answer:

40 years

Step-by-step explanation:

I think 1 score is 20 years

so 2 scores = 2 x 20 = 40 years

I may be wrong so someone check

-Chetan K

In the figure, lines j and k intersect to form the
angles shown. What is the measurements of angle 1

Answers

It’s also 70 degrees because the angles are vertical. In vertical angles angles across from each other are the same and angles next to each other are 180-(the angle number given) so the angle next to 70 would be equal to 110.


5
Find the arc length of the semicircle.
Elther enter an exact answer in terms of or use 3.14 for and enter your answer as a decimal,
units

Answers

Answer:

area is 39.27

Step-by-step explanation:

!!Help!!
solve for x​

Answers

WXY = XYW ( = 41 ) ⇒  XYW is a isosceles triangle

⇒ XW = YW

⇒ 54 = 6x + 6

⇒ 6( x + 1 ) = 54

⇒ x + 1 = 9

⇒ x = 8

ok done. Thank to me :>

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