For each <em>x</em> in the interval 0 ≤ <em>x</em> ≤ 5, the shell at that point has
• radius = 5 - <em>x</em>, which is the distance from <em>x</em> to <em>x</em> = 5
• height = <em>x</em> ² + 2
• thickness = d<em>x</em>
and hence contributes a volume of 2<em>π</em> (5 - <em>x</em>) (<em>x</em> ² + 2) d<em>x</em>.
Taking infinitely many of these shells and summing their volumes (i.e. integrating) gives the volume of the region:
Options:
a. Nikki's proposed placement will light a greater area than Dylan's placement.
b. Dylan's proposed placement will light a greater area than Nikki's placement.
c. Both proposed placements will light the same sized area.
d. Nikki's proposed placement will light more than half the yard.
e. Dylan's proposed placement will light more than half the yard.
f. Dylan's proposed placement will light exactly half of the yard.
g. Nikki's proposed placement will light less than half of the yard.
Answer:
C) Both proposed placements will light the same sized area.
F) Dylan's proposed placement will light exactly half of the yard.
Step-by-step explanation:
The area of a triangle is (base x height) / 2, and both lights illuminate the same base and height = (60 x 38) / 2 = 1,140 sq ft
Both Dylan's and Nikki's proposed placement will lit exactly half of the yard. The yard's total area = 60 x 38 = 2,280 sq ft, which is twice the area lit by the lights.
We want to find the mean of two elements in a set, given that we know the other elements of the set and the mean of the whole set.
The answer is: -490
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For a set with N elements {x₁, x₂, ..., xₙ} the mean is given by:
Here we know that:
We want to find the mean of the values of A and B.
First, we can start by writing the equation for the mean:
We can rewrite this as:
And we have 998 ones, then:
Now we have B isolated.
With this, the mean of A and B can be written as:
So we can conclude that the mean of the other two numbers is -490.
If you want to learn more, you can read: