A contractor is setting up new accounts for the local cable company. She earns $75 for each customer account she sets up. Which
2 answers:
You might be interested in
Answer:
Step-by-step explanation:
The volume of a cuboid can be determined simply by the formula: V= LWH
(where: L is length, H is height and W is width).
In this particular case the base is a square, which means the length and width are equal. Hence we can modify the equation of volume:
Now we need to find the value of H in terms of L. For this we can develop the equation for cost incurred in building the storage shed. We find the area of each side of the cuboid, and then we multiply it by cost per square feet to find the total cost incurred; as shown below:
<u>Area:</u>
Base: ×
Roof: ×
Side: ×
(we have considered all four sides)
<u>Cost:</u>
Base: 4
Roof: 2
Side:
Total cost:
4 + 2
+ 10
= 450
We simplify this equation further:
6 + 10<em>HL </em>= 450
10HL = 450 - 6
We now have the value of H, which we can substitute in the formula of Volume we deduced earlier:
substituting in
:
×
Simplifying it further:
×
is the final answer.
(a) See the attached sketch. Each shell will have a radius <em>y</em> chosen from the interval [2, 4], a height of <em>x</em> = 2/<em>y</em>, and thickness ∆<em>y</em>. For infinitely many shells, we have ∆<em>y</em> converging to 0, and each super-thin shell contributes an infinitesimal volume of
2<em>π</em> (radius)² (height) = 4<em>πy</em>
Then the volume of the solid is obtained by integrating over [2, 4]:
(b) See the other attached sketch. (The text is a bit cluttered, but hopefully you'll understand what is drawn.) Each shell has a radius 9 - <em>x</em> (this is the distance between a given <em>x</em> value in the orange shaded region to the axis of revolution) and a height of 8 - <em>x</em> ³ (and this is the distance between the line <em>y</em> = 8 and the curve <em>y</em> = <em>x</em> ³). Then each shell has a volume of
2<em>π</em> (9 - <em>x</em>)² (8 - <em>x</em> ³) = 2<em>π</em> (648 - 144<em>x</em> + 8<em>x</em> ² - 81<em>x</em> ³ + 18<em>x</em> ⁴ - <em>x</em> ⁵)
so that the overall volume of the solid would be
I leave the details of integrating to you.
