Eric found that about 62% of 80 classmates at school like pop music. However, 70% of his 60 relatives like pop. About how many c
1 answer:
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9514 1404 393
Answer:
(c) 1.649
Step-by-step explanation:
For a lot of these summation problems it is worthwhile to learn to use a calculator or spreadsheet to do the arithmetic. Here, the ends of the intervals are 1 unit apart, so we only need to evaluate the function for integer values of x.
Almost any of these numerical integration methods involve some sort of weighted sum. For <em>trapezoidal</em> integration, the weights of all of the middle function values are 1. The weights of the first and last function values are 1/2. The weighted sum is multiplied by the interval width, which is 1 for this problem.
The area by trapezoidal integration is about 1.649 square units.
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In the attached, we have shown the calculation both by computing the area of each trapezoid (f1 does that), and by creating the weighted sum of function values.
Split the surface area into geometric shapes as shown in the figure below.
Top part
The area of one triangle is
A₁ = (1/2)*(10 cm)*(4 cm) = 20 cm²
There are 3 of these triangles.
Vertical sides..
The area of one vertical side is
A₂ = (10 cm)*(6 cm) = 60 cm²
There 3 of them.
Bottom part
The triangle is equilateral with each side = 10 cm, and each angle = 60 deg.
The area is (from the Law of Sines) equal to
A₃ = (1/2)(10 cm)*(10 cm)*sin(60) = 43.3 cm²
The total surface area is
3A₁ + 3A₂ + A₃
= 3*20 + 3*60 + 4.3
= 283.3 cm²
Answer: The surface area is 283.3 cm²
Top part
The area of one triangle is
A₁ = (1/2)*(10 cm)*(4 cm) = 20 cm²
There are 3 of these triangles.
Vertical sides..
The area of one vertical side is
A₂ = (10 cm)*(6 cm) = 60 cm²
There 3 of them.
Bottom part
The triangle is equilateral with each side = 10 cm, and each angle = 60 deg.
The area is (from the Law of Sines) equal to
A₃ = (1/2)(10 cm)*(10 cm)*sin(60) = 43.3 cm²
The total surface area is
3A₁ + 3A₂ + A₃
= 3*20 + 3*60 + 4.3
= 283.3 cm²
Answer: The surface area is 283.3 cm²