1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Masteriza [31]
3 years ago
15

A rectangular box is to have a square base and a volume of 40 ft3. If the material for the base costs $0.36/ft2, the material fo

r the sides costs $0.05/ft2, and the material for the top costs $0.14/ft2, determine the dimensions of the box that can be constructed at minimum cost.length ftwidth ftheight ft
Mathematics
1 answer:
blagie [28]3 years ago
6 0

Answer:

  • length: 2 ft
  • width: 2 ft
  • height: 10 ft

Step-by-step explanation:

The total cost of the top and bottom is $0.36 + 0.14 = $0.50 per square foot.

The total cost of a pair of opposite sides is $0.05 +0.05 = $0.10 per square foot.

A minimum-cost box will have the cost of any pair of opposite sides be the same. Here, that means the box will have a side area that is 5 times the area of the top or bottom.

Since the base is square, that means the box is the shape of 5 cubes stacked one on the other. Each of those would be 8 ft³, so would have edge dimensions of ∛8 = 2 feet. The height is 5 times that, or 10 ft.

The box is 2 feet square by 10 feet high:

  • length: 2 ft
  • width: 2 ft
  • height: 10 ft

_____

If you feel the need to write an equation, you can let x represent the edge length of the base. Then the cost of the top and bottom will be ...

  top&bottom cost = 0.50·x²

The height of the box is 40/x², so the cost of the four sides will be ...

  side cost = (0.05)(4x)(40/x²) = 8/x

This is minimized when the derivative of the sum of these costs is zero:

  cost = top&bottom cost + side cost

  cost = 0.50x² + 8/x

  d(cost)/dx = 1.00x -8/x² = 0

Multiplying by x², we get ...

  x³ -8 = 0

  x = ∛8 = 2 . . . . . . as above

  height = 40/x² = 40/4 = 10 . . . . . as above

You might be interested in
Angel has an action figure collection of 300 action figures. He keeps 267 of the action figures on his wall. What percentage of
Veseljchak [2.6K]

Answer:

89% of Angel's action figure collection keeps on his wall.

Step-by-step explanation:

<u>Percentages</u>

To calculate the X% of a quantity Y, we must multiply both numbers and divide by 100:

X% of Y = X * Y / 100

For example, 15% of 780 = 15 * 780 / 100 = 117

If we want to know what percentage is m with respect to n, we proceed as follows:

percentage = m / n * 100%

Anges has a 300 action figures collection, 267 of which are kept on his wall. Here m=267, n=300, thus:

percentage = 267 / 300 * 100% = 89%

89% of Angel's action figure collection keeps on his wall.

5 0
4 years ago
Risk taking is an important part of investing. In order to make suitable investment decisions on behalf of their customers, port
GrogVix [38]

Answer:

a=49.5 -1.28*15=30.3

So the value of height that separates the bottom 10% of data from the top 90% is 30.3.  

If the score is lower than 30.3 we consider this score as risk averse

Step-by-step explanation:

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".  

Solution to the problem

Let X the random variable that represent the scores of a population, and for this case we know the distribution for X is given by:

X \sim N(49.5,15)  

Where \mu=49.5 and \sigma=15

We are interested in the bottom 10% of the data.

For this part we want to find a value a, such that we satisfy this condition:

P(X>a)=0.9   (a)

P(X   (b)

Both conditions are equivalent on this case. We can use the z score again in order to find the value a.  

As we can see on the figure attached the z value that satisfy the condition with 0.1 of the area on the left and 0.9 of the area on the right it's z=-1.28. On this case P(Z<-1.28)=0.1 and P(z>-1.28)=0.9

If we use condition (b) from previous we have this:

P(X  

P(z

But we know which value of z satisfy the previous equation so then we can do this:

z=-1.28

And if we solve for a we got

a=49.5 -1.28*15=30.3

So the value of height that separates the bottom 10% of data from the top 90% is 30.3.  

If the score is lower than 30.3 we consider this score as risk averse

7 0
3 years ago
Reagan jars 6 liters of jam every day. How much jam did Reagan jar if she spent 3 days making jam?
Andrei [34K]
She spent 18 liters of jam!
5 0
3 years ago
A truck has a trailer that has a length of
bija089 [108]

Answer:

56m cubed

Step-by-step explanation:

7m×2m×4m=56m

5 0
3 years ago
Identify the properties used for the first two steps in simplifying 6ab2 + 4a2b – 3ab2 + 3a2b – 2a2b2.
Kryger [21]
The expression 6ab^2+4a^2b-3ab^2+3a^2b-2a^2b^2 has two similar pairs of <span>conjunctions.
</span>
1. Rewrite this expression as
6ab^2+4a^2b-3ab^2+3a^2b-2a^2b^2=
=(6ab^2-3ab^2)+(4a^2b+3a^2b)-2a^2b^2
and then 
2. add the similar <span>conjunctions
</span><span>
</span><span>(6ab^2-3ab^2)+(4a^2b+3a^2b)-2a^2b^2=3ab^2+7a^2b-2a^2b^2.</span><span>
</span><span />

3 0
4 years ago
Read 2 more answers
Other questions:
  • Solve the equations below for x. Please show your math work step by step.
    15·1 answer
  • Help me with this question please!<br> (Look at image!)
    15·2 answers
  • Which statement is true about f(x)-2/3lx+4l-6?
    12·2 answers
  • Just over 3 quarters of Canadians live within a short distance of the USA border. Write this fraction as a decimal.
    15·1 answer
  • A middle school with 375 students has 125 students in the eighth grade. Irene says that the eighth-grade class makes up of the s
    9·1 answer
  • Find the probability of this event. Enter the answer as a fraction in simplest form, as a decimal, and as a
    12·1 answer
  • DUE Tomorrow!!<br> is this answer correct?
    13·1 answer
  • If f(x)= 3x^3+4 find f(-3)
    12·1 answer
  • GIVING BRAINLY!
    6·1 answer
  • 8 pleaseeeee help meeeee!
    11·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!