Answer:
27
Step-by-step explanation:
9 crew members complete a job in 3 months
Number of crew members is inversely proportion to construction time :
Let :
Crew members = m
Construction time = t
m α 1 /t
m = k/t
m = 9 ; t = 3
9 = k /3
k = 27
If t = 1 (one month)
m =?
m = k/t
m = 27 / 1
Hence;
m = 27 * 1
m = 27 workers
The smallest amount of material needed is 54 square centimeters
<h3>How to determine the amount of material needed?</h3>
The given parameters are:
Volume = 36 cubic centimeters
Represent length with x, width with y and height with z.
So, we have
x = 3y
The volume is calculated as:
V = xyz
This gives
V = 3y²z
Substitute 36 for V
3y²z = 36
Divide by 3
y²z = 12
Make z the subject
z = 12/y²
The surface area is:
S = 2(xy + xz + yz)
This gives
S = 2(3y² + 3yz + yz)
Evaluate the like terms
S = 2(3y² + 4yz)
Expand
S = 6y² + 8yz
Substitute z = 12/y²
S = 6y² + 8y * 12/y²
This gives
S = 6y² + 96/y
Differentiate
S' = 12y - 96/y²
Set to 0
12y - 96/y² = 0
Multiply through by y²
12y³ - 96 = 0
Add 96 to both sides
12y³ = 96
Divide by 12
y³ = 8
Take the cube root of both sides
y = 2
Recall that:
x = 3y and z = 12/y²
This gives
x = 3 * 2 = 6
z = 12/2² = 3
Recall that:
S = 2(xy + xz + yz)
So, we have:
S = 2(6 * 2 + 3 * 3 + 2 * 3)
Evaluate
S = 54
Hence, the smallest amount of material needed is 54 square centimeters
Read more about surface areas at:
brainly.com/question/76387
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Answer:
The lateral area of the pipe is 942 sq ft.
Step-by-step explanation:
A pipe can be modeled as a cylinder prism.
The lateral area of a cylinder prism can be expressed as the product of the length by the perimeter of the section.
We start by calculating this perimeter.
As the diameter is 25 ft, the perimeter of the section can be expressed as:
Then, to know the lateral surface we multiply this perimeter by the length of the pipe (12 ft):
The lateral area of the pipe is 942 sq ft.
1 - True. If a number is divisible by 12 it's divisible by 6 and thus by 3
2 - False. A rhombus needn't have square angles
3 - False. the second proposition is unrelated to the first one, and doesn't allow us to deduce that cats have fur.
4 - False - We cannot link the first and second proposition in any way to make the third