The reinforced box with dimensions of 10√10 inches by 10√10 inches by 10 inches have costs the least compare to minimum surface area.
Plan for solving problem,
Minimize the surface area of the box subject to the constraint that the volume is 10,000 cubic inches.
Since the base of the box is a square, let's denote the length of each side of the base as x.
Height of the box will be h = 10000/x^2 to satisfy the volume constraint.
Surface area of the box is,
A = 2x^2 + 4xh
Find the values of x and h that minimize A.
Take the derivative of A with respect to x, set it equal to zero to find critical points.
Use the second derivative test to determine whether each critical point is a minimum or maximum.
Find the dimensions of the box with minimum surface area.
Then determine the dimensions of reinforced box that costs the least .
By adding up cost of top and walls at 1 cent /in² and cost of bottom at 2 cents /in² for those dimensions.
Now solution is,
Minimize the surface area of the box,
A = 2x^2 + 4xh
Subject to the constraint that the volume is 10,000 cubic inches,
V = x^2 h
= x^2 (10000/x^2)
= 10000
System of equations is,
x^2 h = 10000
⇒h = 10000/x^2
Substituting the second equation into the expression for A,
A = 2x^2 + 4x(10000/x^2)
= 2x^2 + 40000/x
Critical points of A, take the derivative with respect to x and set it equal to zero,
A' = 4x - 40000/x^2
⇒4x - 40000/x^2 = 0
Solving for x,
⇒x = 10√10
To confirm that this is a minimum, we take the second derivative of A with respect to x,
A'' = 4 + 80000/x^3
Plugging in x = 10√10,
A'' = 4 + 80000/(10√10)^3
≈ 6.53 >0
Since A'' is positive, the critical point x = 10√10 is a minimum.
Dimensions of the box with minimum surface area are,
Base, x = 10√10 inches
Height,
h = 10000/x^2
= 10000/(10√10)^2
= 10inches
Dimensions of the reinforced box that costs the least,
Cost of top and walls at 1 cent /in² and cost of the bottom at 2 cents /in² for these dimensions,
Cost of top and walls,
2x^2 + 4xh
= 2(10√10)^2 + 4(10√10)(10)
= 3265 square inches at 1 cent /in²
= $32.65
Cost of bottom,
x^2
= (10√10)^2
= 1000 square inches at 2 cents /in²
= $20.00
Therefore, the reinforced box with dimensions of 10√10 inches by 10√10 inches by 10 inches and a reinforced bottom costs the least.
learn more about dimensions here
brainly.com/question/18940984
#SPJ4
Find the values of X and Y
In a triangle, The value of x is, 40°
And, The value of y is, 50°
What is mean by Triangle?A triangle is a three sided polygon, which has three vertices and three angles which has the sum 180 degrees.
We have to given that;
The triangle is show in figure.
We know that;
In a triangle, the pair of two opposite sides are equal then there corresponding angles are also equal.
Now, By figure we can formulate;
⇒ x + x + 100 = 180
Solve for x;
⇒ 2x + 100 = 180
⇒ 2x = 180 - 100
⇒ 2x = 80
⇒ x = 40
Thus, The value of x = 40°
And, We get;
⇒ x° + y° + 90° = 180°
⇒ 40 + y + 90 = 180
⇒ y + 130 = 180
⇒ y = 180 - 130
⇒ y = 50°
Thus, The value of y = 50°
Learn more about the triangle visit;
brainly.com/question/1058720
#SPJ1
4 1/8 divided by what equals 2 1/6
Answer:
\(\frac{41}{28}\)
I hope this helps!
Suppose bob's exam score was at the 80th percentile on an exam whose mean was 90. what was bob's exam score?
The mean score of 90, and percentile of Bob's score of 80, gives Bob's exam score as approximately 92.5%
What is the formula that gives the exam score from the percentile?The Z-Score of the 80th percentile is 0.8416
The formula for Z-Score is presented as follows;
\(z = \frac{x - \mu}{ \sigma} \)
Where;
\( \sigma = The \: standard \: deviation\)
\( \mu = The \: mean = 90\%\)
x = The given score
Taking the mean as a proportion, we have;
\( \sigma = \sqrt{\frac{\mu \cdot (1-\mu)}{n}}\)
Which gives;
\( \sigma = \sqrt{\frac{0.9 \times (1-0.9)}{100}}= 0.03\)
Therefore, when z = 0.8416, gives;
\(0.8416 = \frac{x - 0.9}{ 0.03} \)
x = 0.8416 × 0.03 + 0.9 ≈ 0.925
Therefore;
Bob's exam score is approximately 92.5%Learn more about Z-Score here:
https://brainly.com/question/25638875
#SPJ4
how do I do a dilation? I'm in 8th grade and failing cuz I don't understand?
Answer:
Starting with ΔABC, draw the dilation image of the triangle with a center at the origin and a scale factor of two.Dilations involve multiplication. Dilation with scale factor 2, multiply by 2.
20. Suppose that the temperature in Algebra Crater on Planet Math is at its lowest
recorded value (-30°F). If the temperature rises by 8 degrees every hour, what will
the temperature be in Algebra Crater after six hours have passed?
o this space for scratch work.
The temperature in the Algebra Crater after 6 hours will be 18°F
The temperature in the Algebra Crater on the planet Math is = -30°F
It is given that the temperature rises by 8 degrees every hour, therefore
we have to find the temperature after 6 hour.
The rise in temperature after 6 hour will be = 6*8°F
= 48°F
That is there will be 48°F rise in temperature after 6 hour.
Thus the temperature after 6 hours in the algebra Craters will be
= -30°F + 48°F
= 18°F
Hence the temperature in the Algebra Crater after 6 hours will be 18°F
Learn more about temperature here : https://brainly.com/question/24746268
#SPJ9
in a certain amount of time, a plane traveling at a constant $250$ miles per hour traveled $20,\!000$ feet. in this same amount of time, how many feet would a plane traveling at a constant $400$ miles per hour travel?
At a constant rate of 400 miles per hour travel, the plane would be travelling from 32000 feet above the land.
The speed of an object is the ratio of distance and time it takes for the object to travel that distance.
Mathematically,
S = D/T
where
S is velocity
D is the distance traveled or distance traveled
T is the time it takes to travel that distance
Velocity is considered a scalar quantity. A scalar size only has a size. It does not provide information about the direction of object movement.
If an object moves at a constant speed, it means that the object moves the same distance in the same time interval.
Acceleration of an object is the ratio of velocity and time. vector size. Vector quantities have both magnitude and direction.
Mathematics,
a = v/t
When an object is in motion, its acceleration is never zero.
When an object moves, it moves a constant distance over time. Therefore, body positions cannot be the same from the same coordinate system.
Given in the question:
First the plane was travelling at a constant rate of 250 miles per hour.
Initial height was 20000 feet
Now,
As the speed increases and travels at a constant rate of 400 miles per hour.
Now,
(400 /250 ) × 20000
= 1.6 × 20000
= 32000 feet
Thus, At a constant rate of 400 miles per hour travel, the plane would be travelling from 32000 feet above the land.
Learn more about Constant Rate:
https://brainly.com/question/13659182
#SPJ4
What will be the coefficient of XYZ in the product of 2xy 3zx and Y 2z )?
The coefficient of XYZ in the product of 2xy 3zx and Y 2z is 0.
The formula for coefficient is C = a*b, where a and b are the coefficients of the terms being multiplied.
In the given example, the coefficients for the terms being multiplied are 2 for 2xy, 3 for 3zx, and 0 for Y 2z. Since 0 multiplied by any number is 0, the coefficient of XYZ in the product is 0.
Mathematically, this can be expressed as:
C = 2*3*0 = 0
Therefore, the coefficient of XYZ in the product of 2xy 3zx and Y 2z is 0.
Learn more about coefficient here:
https://brainly.com/question/28975079
#SPJ4
What are the coordinates of(D0. 25∘rx-axis)(ABCD) for A(2, 6), B(0, 0), C(-5, 8), and D(-2, 10)?
(express ordered pairs as decimal)
The coordinates of point D 0.25 x-axis for the points A(2, 6), B(0, 0), C(-5, 8), and D(-2, 10) are (-2, -2.5) when point D is reflected across the x-axis. This is obtained by negating the y-coordinate of point D and keeping the x-coordinate the same.
To find the coordinates of point D 0.25 x-axis, we need to reflect point D across the x-axis. This will result in the y-coordinate of point D being negated while the x-coordinate remains the same.
The coordinates of point D are (-2, 10), so when we reflect it across the x-axis, we get the new coordinates:
D 0.25 x-axis = (-2, -10/4) = (-2, -2.5)
Therefore, the coordinates of point D0.25∘rx-axis for the given points A, B, C, and D are (-2, -2.5).
Learn more about graphs here: brainly.com/question/17267403
#SPJ4
\(5+\frac{x}{2} \geq 10\)
D) Show the surface area and volume of a sphere with radius r is 4èr² and 4 .3 ³ respectively. 3
The surface area of a sphere with radius r is 12.56r² and the volume is 4.19r³.
Given the radius of a sphere as r. We are required to find the surface area and volume of a sphere. Surface area of the sphere: The formula for the surface area of the sphere is 4πr².π = 3.14. Putting the value of π, we get:
Surface area of the sphere
= 4πr²
= 4×3.14×r²
= 12.56r²
Volume of the sphere: The formula for the volume of the sphere is given as $\frac{4}{3}$πr³
Putting the value of π, we get,
Volume of the sphere = $\frac{4}{3}$πr³= $\frac{4}{3}$ × 3.14 × r³= 4.19r³
Thus, the surface area of a sphere with radius r is 12.56r² and the volume is 4.19r³.
To know more about sphere visit:
brainly.com/question/27578223
#SPJ11
What number is
10 times as much
as 90
Answer:
900
Step-by-step explanation:
10 x 90 = 900
Answer:
900
Step-by-step explanation:
my brain
A whole number is 6 more than 2 times another number. The sum of the two numbers is less than 50. This can be written in an inequality as x + 2x + 6 < 50, where x represents the smaller number.
The solution to the system of equation is x < 44/3
Expansion of inequality expressionsInequality expressions are expressions not separated by an equal sign. An example of an inequality is a < b
Given the inequality expression below;
x + 2x + 6 < 50
Simplify to have:
3x + 6 < 50
Subtract 6 from both sides
3x + 6 - 6 < 50 - 6
3x < 50 - 6
3x < 44
Divide both sides by 3
3x/3 < 44/3
x < 44/3
Hence the solution to the system of equation is x < 44/3
Learn more on inequality here: https://brainly.com/question/24372553
#SPJ1
claim: at most 28% of internet users pay bills online. A recent survey of 326 internet users indicated that 25% pay their bills online
bills refer to invoices or statements issued to request payment for goods or services provided. They typically outline the amount owed, due date, and payment instructions.
Based on the claim that at most 28% of internet users pay bills online, we need to determine if the recent survey supports or contradicts this claim.
The recent survey of 326 internet users indicated that 25% pay their bills online. To determine if this supports the claim, we need to compare the survey result to the claim.
Since the claim states "at most" 28% of internet users pay bills online, it means that 28% is the maximum percentage. Therefore, if the survey result of 25% falls within this range, it supports the claim.
To calculate this, we subtract the survey result (25%) from the maximum claim (28%):
28% - 25% = 3%
Since the difference is 3%, which is a positive value, the survey result of 25% falls within the maximum claim of 28%. Therefore, the recent survey supports the claim that at most 28% of internet users pay bills online.
To know more about bills visit:
https://brainly.com/question/3816875
#SPJ11
plz anser i will giv brainliest
When a random representative sample is drawn from a population, the procedure is deemed to be what type of sample?
The procedure which is deemed to be the type of sample in discuss is; representative sample are free of bias.
What is a random sampling?Representative sampling and random sampling are two techniques used to help ensure data is free of bias. A representative sample on the other hand is a group or set chosen from a larger statistical population according to specified characteristics. A random sample is a group or set chosen in a random manner from a larger population.
Read more on representative sampling;
https://brainly.com/question/25142707
#SPJ4
For which pair of functions is (gof)(a) = al-2? O f(a) = a? – 4 and g(a) = Va o fla) = 3a-1 and g(a) = 2a - 2 O f(a) = 5 + a² and g(a) = a-5-2 O f(a) = 3 - 3a and g(a) = 4a - 5
Step-by-step explanation:
f(a)=1/2-1 and g(a)=2a-2
The pair of functions that gives
f(a) = 5 + a² and g(a) = √(a - 5) - 2 is (g o f) (a) = |a| - 2.
Option C is the correct answer.
What is a function?A function has an input and an output.
A function can be one-to-one or onto one.
It simply indicated the relationships between the input and the output.
Example:
f(x) = 2x + 1
f(1) = 2 + 1 = 3
f(2) = 2 x 2 + 1 = 4 + 1 = 5
The outputs of the functions are 3 and 5
The inputs of the process are 1 and 2.
We have,
f(a) = a² - 4 and g(x) = √a
(g o f) (a)
= g (f(a))
= g (a² - 4)
= √(a² - 4)
f(a) = (1/2)a - 1 and g(a) = 2a - 2
(g o f) (a)
= g (f(a))
= g ((1/2)a - 1)
= 2 x ((1/2)a - 1) - 2
= a - 2 - 2
= a - 4
f(a) = a² - 4 and g(a) = √a
(g o f) (a)
= g (f(a))
= g (a² - 4)
= √(a² - 4)
f(a) = 5 + a² and g(a) = √(a - 5) - 2
(g o f) (a)
= g (f(a))
= g (5 + a²)
= √((5 + a² - 5) - 2
= √a² - 2
= |a| - 2
f(a) = 3 - 3a and g(a) = 4a - 5
(g o f) (a)
= g (f(a))
= g (3 - 3a)
= 4(3 - 3a) - 4
= 12 - 12a - 4
= 8 - 12a
Thus,
The pair of functions that gives
f(a) = 5 + a² and g(a) = √(a - 5) - 2 is (g o f) (a) = |a| - 2.
Learn more about functions here:
https://brainly.com/question/28533782
#SPJ7
I HAVE 13 MINS LEFT HURRY PLEASE
If $3,200 is invested at a rate of 5.5%, compounded quarterly, calculate the value of the investment after
4 years. Round to the nearest dollar.
Hint: Use the formula below
A=P(1+r/n)^nt
Answer:
A = $13,366.37
A = P + I where
P (principal) = $10,000.00
I (interest) = $3,366.37
Step-by-step explanation:
Answer:
$3964
Step-by-step explanation:
A=P(1+r/n)^nt
So 3964(1+.055)^4
Comes out to 3964.238882. Then round
Hope this helps
Brainliest would be appreciated
it is used to represent the product
A 35.0 V battery with negligible internal resistance, a 50.0 12 resistor, and a 1.25 mH inductor with negligible resistance are all connected in series with an open switch. The switch is suddenly closed. Part A For related problemsolving tips and strategies, you may want to view a Video Tutor Solution of Analyzing an r- circuit. How long after closing the switch will the current through the inductor reach one-half of its maximum value? Express your answer with the appropriate units.
The current through the inductor to reach one-half of its maximum value after closing the switch is approximately 12.5 microseconds.
How long does it take for the current through the inductor to reach half of its maximum value after the switch is closed?To determine the time it takes for the current through the inductor to reach one-half of its maximum value, we can use the time constant formula for an RL circuit:
t = (1/2)(L/R)
Given:
Voltage (V) = 35.0 VResistance (R) = 50.0 ΩInductance (L) = 1.25 mH = 0.00125 HPlugging in the values, we have:
t = (1/2)(0.00125 H) / (50.0 Ω)
Simplifying the equation, we find:
t = 0.0000125 s or 12.5 μs
Therefore, the current through the inductor will reach one-half of its maximum value approximately 12.5 microseconds after closing the switch.
Learn more about current
brainly.com/question/31315986
#SPJ11
Suppose you learn a word embedding for a vocabulary of 10000 words. Then the embedding vectors should be 10000 dimensional, so as to capture the full range of variation and meaning in those words.
True
False
False. The statement is not necessarily true. While it is possible to have word embeddings that are 10000 dimensional for a vocabulary of 10000 words.
It is not a requirement to capture the full range of variation and meaning in those words. The dimensionality of word embeddings is not solely determined by the size of the vocabulary, but rather by various factors such as the complexity of the underlying semantic relationships and the specific modeling techniques used.
In practice, word embeddings are often created using techniques like Word2Vec or GloVe, which typically produce lower-dimensional embeddings (e.g., 100 to 300 dimensions). These lower-dimensional embeddings have been shown to effectively capture important semantic relationships and patterns in language, while also reducing the computational complexity and memory requirements. The choice of dimensionality depends on the specific application and the trade-off between capturing sufficient information and computational efficiency.
To know more about vectors click here: brainly.com/question/24256726
#SPJ11
Is y=12 x+3 a proportional relationship
Answer:
no
Step-by-step explanation:
A proportional relationship is of the form
y = kx
This is equation is of the form
y = kx+b
They are not the same so it is not a proportional relationship
How can I divide so fast?
To divide fast we need to practice the Long division method more and more
What are long division method and its steps?
When splitting huge numbers, the task is divided into several sequential parts using the long division approach. The dividend is divided by the divisor, just as in conventional division problems, and the result is known as the quotient; occasionally, it also produces a remainder.
We need to comprehend a few stages to divide. A vinculum or right parenthesis separates the dividend from the quotient, while a vertical bar separates the divisor from the dividend. Let's now go through the long division stages listed below to comprehend the procedure.
1. Take the dividend's first digit starting from the left. Verify if this digit exceeds or is equal to the divisor.
2. Next, divide it by the divisor, and write the result as the quotient on top.
3. Subtract the outcome from the digit, and then put the difference below.
Step 4: Decrease the dividend's subsequent digit (if present).
Step 5: Carry out Step 4 again.
Learn more about Long division from the link below
brainly.com/question/28824872
#SPJ4
Richard Gaziano is a manager for Health Care, Inc. Health Care deducts Social Security, Medicare, and FIT (by percentage method) from his earnings. Assume a rate of 6.2% on $118,500 for Social Security and 1.45% for Medicare. Before this payroll, Richard is $1,000 below the maximum level for Social Security earnings. Richard is married, is paid weekly, and claims 2 exemptions. What is Richard’s net pay for the week if he earns $1,700?
Richard's net pay for the week, considering Social Security, Medicare, and FIT deductions, can be calculated by subtracting the total deductions from his gross earnings.
First, let's determine the amount deducted for Social Security. The Social Security rate is 6.2%, and the maximum earnings subject to this deduction are $118,500. Since Richard is $1,000 below the maximum level, the amount subject to Social Security deduction is $1,000. Therefore, the Social Security deduction is 6.2% of $1,000.
Next, we calculate the Medicare deduction. The Medicare rate is 1.45%, and it is applied to the entire earnings of $1,700.
To calculate the FIT deduction, we need additional information about Richard's taxable income, tax brackets, and exemptions. Without this information, we cannot provide an accurate calculation for the FIT deduction.
Finally, we subtract the total deductions (Social Security, Medicare, and FIT) from Richard's gross earnings of $1,700 to obtain his net pay for the week.
Learn more about subtract here: brainly.com/question/28008319
#SPJ11
if the cost of groceries gone up by 7% each year than how much would a hundred dolars worth of groceries cost in three years
The worth of the 100 dollar worth if groceries in 3 years is
What is exponential function?An exponential function is a Mathematical function in the form f (x) = ax, where “x” is a variable and “a” is a constant which is called the base of the function and it should be greater than 0. The most commonly used exponential a base is the transcendental number e, which is approximately equal to 2.71828.
Using the formula:
P(t) = P(o) e ^kt
k =7/100 = 0.07
t = 3years
P(o) = $100
P(t) = 100 e^0.07×3
P(t) = 100e^0.21
P(t) =100×1.23
P(t) = $123
therefore the worth of the $100 groceries in 3 years is $123
learn more about exponential function from
https://brainly.com/question/2456547
#SPJ1
who wants to help i really dont wanna do this question
Answer:
71
Step-by-step explanation:
(2x² = 2 × 5² = 2 × 25) + ([4x = 4 × 5 = 20] + 1)
(50) + (21) = 71
Please please help me i'm begging you!
Answer:
A is 8 ounces/ 12 cupcakes is 12 cupcakes/8 ounces I'm not sure about C and D is 18 cupcakes for 12 ounces of frosting
Step-by-step explanation:
Find the volume of a sphere with a diameter of 32mm
We want to find the volume of the sphere with a diameter of 32 mm.
The formule for obtaining the volume of a sphere is;
\(V=\frac{4}{3}\pi r^3\)Where r is the radius, the radius is half of the diameter, so ;
\(r=\frac{32}{2}=16\operatorname{mm}\)We can now calculate the volume as;
\(V=\frac{4}{3}\times\pi\times16^3\)\(V=17157.28\operatorname{mm}^3\)can you explain each step please for i can write it on a paper along with you
The two groups are given one is those who are studied and other is those who are not studied.
Studied - 88,100,94,79,92,100,95,83,89,99,100,91,89,95,100,93,96,84.
Arrange in order.
79, 83, 84, 88, 89, 89, 91, 92, 93, 94, 95, 95, 96, 99, 100, 100, 100, 100
The mean of this group is
\(\frac{88+100+94+79+92+100+95+83+89+99+100+91+89+95+100+93+96+84}{18}\)\(\frac{1667}{18}=92.6\)The mean is 92.6.
The median of this group is
Use the median formula for even
\(m=\frac{(\frac{n}{2})^{th}+(\frac{n}{2}+1)^{th}^{}}{2}\)Substitute the value of n =18
\(m=\frac{(\frac{18}{2})^{th}+(\frac{18}{2}+1)^{th}^{}}{2}=\frac{9^{th}+10^{th}^{}}{2}\)\(m=\frac{93+94}{2}=93.5\)The median is 93.5.
The mode of this group is 100 as it is appears 3 times .
The another group is not studied group.
Not studied - 82,72,45,91,58,83,65,87,90,77,73,89.
Arrange in order-
45, 58, 65, 72, 73, 77, 82, 83, 87, 89, 90, 91
The mean is determined as
\(\frac{82+72+45+91+58+83+65+87+90+77+73+89}{12}=\frac{912}{12}=76\)The median is determined as
\(m=\frac{(\frac{n}{2})^{th}+(\frac{n}{2}+1)^{th}}{2}\)Substitute n=12.
\(m=\frac{(\frac{12}{2})^{th}+(\frac{12}{2}+1)^{th}^{}}{2}=\frac{6^{th}+7^{th}}{2}=\frac{77+82}{2}=79.5\)There is no mode.
So, from the all the data given.
The mean of the group that studied is over 15 percent points higher than the mean of the group that did not studied.
\(92.61-76=16.61\)The median of the group that did not studied is less than 80.
In general , those students that studied scored much higher than those students that did not study.
The correct options are a , c and e.
Becky is shipping 5 boxes that all weigh the same, and 1 enevelope that weighs 7.5
pounds. The total weight of the shipment is 65 pounds. what is the weight in pounds of
each box?
OA. 5.5
OB. 11.5
O C. 14.5
O D. 20.5
K
Each box weighs 11.5 pounds. The answer is option B.
What is Pound?Pound is a unit of measurement of mass or weight commonly used in the United States and some other countries, abbreviated as "lb".
According to question:To solve the problem, we need to use some basic algebraic equations. Let x be the weight of each box in pounds. Then, we can set up the following equation:
5x + 7.5 = 65
Simplifying this equation, we get:
5x = 57.5
Dividing both sides by 5, we get:
x = 11.5
Therefore, each box weighs 11.5 pounds. The answer is option B.
Pound is a unit of measurement of mass or weight commonly used in the United States and some other countries, abbreviated as "lb". One pound is equal to 16 ounces, and approximately 0.45 kilograms. It is commonly used to measure the weight of objects, such as people, animals, and goods.
Learn more about pounds visit:
https://brainly.com/question/23942137
#SPJ1
suppose the number of customers visiting a shoe store follows a poisson process with a rate of 70 per day. assume 45 percent of customers make a purchase. the amount spent by a paying customer follows an exponential distribution with a mean of $120. the two distributions are independent. what is the standard deviation of the total sales per day for the shoe store?
The standard deviation of the total sales per day for the shoe store is approximately $1743.28.
To find the standard deviation of the total sales per day for the shoe store, we need to first find the mean and variance of the total sales.
The number of customers visiting the store follows a Poisson distribution with a rate of 70 per day. Let X be the number of customers per day, then X ~ Poisson(70).
The proportion of customers that make a purchase is 45%. Let Y be the number of customers that make a purchase, then Y ~ Binomial(X, 0.45).
The amount spent by a paying customer follows an exponential distribution with a mean of $120. Let Z be the amount spent by a paying customer, then Z ~ Exp(1/120).
Now, let's find the mean and variance of the total sales per day.
E[XY] = E[E[XY|X]] = E[X * 0.45] = 70 * 0.45 = 31.5
E[Z] = 120
E[XYZ] = E[E[XYZ|XY]] = E[XY * 120] = 31.5 * 120 = 3780
Var(XY) = E[Var(XY|X)] + Var(E[XY|X]) = E[X * 0.45 * 0.55] + Var(X * 0.45) = 70 * 0.45 * 0.55 + 70 * 0.45 * 0.55 = 17.325
Var(Z) = 120^2
Var(XYZ) = E[Var(XYZ|XY)] + Var(E[XYZ|XY]) = E[XY * 120^2] + Var(XY * 120) = 31.5 * 120^2 + 17.325 * 120^2 = 3035250
Therefore, the variance of the total sales per day is Var(XYZ) = 3035250.
The standard deviation of the total sales per day is the square root of the variance:
SD(XYZ) = sqrt(3035250) = 1743.28
Therefore, the standard deviation of the total sales per day for the shoe store is approximately $1743.28.
To learn more about standard deviation, click here:
https://brainly.com/question/23907081
#SPJ11