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2 years ago

Help I be trying so but can figure out the answer

Mathematics

2 answers:

Ede4ka [16]2 years ago

8 0

Answer:

Step-by-step explanation:

We are to assume the earth is a sphere and the radius has been given in the question which is 3959 miles

Area of a sphere = 4*pi*r^2

Where pi= 22/7 (constant)

r= radius

Area= 4*22/7*3959^2

=4*22/7*15673681

=1379283928/7

=197040561.14 square mile

=197040561.14 mi^2

Total area of the earth has been solved as 197040561.14 mi^2 and 20 percent of this surface area is suitable to live on.

We calculate the 20% thus:

20/100 * 197040561.14 mi^2

=3940811222.8/100 mi^2

=39408112.228mi^2

There are approximately 7.7 billion people on earth that will live on the suitable land with an area of 39408112.228mi^2

Each person in the world will have square mile of

39408112. 228 mi^2 / 7.7billion persons

=39408112.228/7700000000

=0.0051179367mi^2 per person

Approximately, 0.00512mi^2/person (option C)

Check the attachment for better mathematical expressions

Sphinxa [80]2 years ago

4 0

Answer:

Step-by-step explanation:

Surface of the earth =3959×3.14

=12,437.565

if 20%is suitable so we multiply it by the surface

12,437.565×0.2=2,487.513 per people

2,487.513/7,700,00,00

So I think it will be the closest to b

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3x+5=14

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3 years ago

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Find the distance between the points (-1,-9) and (1,-4)

Snezhnost [94]

The distance between the two points is 5.4

Explanation:

The points are (-1,-9) and (1,-4)

The distance between the two points can be determined using the formula

$d=\sqrt{\left(x_{2}-x_{1}\right)^{2}+\left(y_{2}-y_{1}\right)^{2}}$

Substituting the values in the formula, we get,

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Thus, the distance between the two points is 5.4

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2 years ago

What is the domain of the step function f(x) = ⌈2x⌉ – 1?

Alik [6]

Answer:

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Step-by-step explanation:

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3 years ago

Bruno solved the following equation: 4x + one half(10x − 4) = 6 Step Work Justification 1 4x + 5x − 2 = 6 2 9x − 2 = 6 3 9x = 8

beks73 [17]

Answer:

Statement Reason

1. $4x+5x-2=6$ 1. Distributive Property

2. $9x-2=6$ 2. Combine like terms

3. $9x=8$ 3. Addition Property of Equality

4. $x=\dfrac{8}{9}$ 4. Division Property of Equality

Step-by-step explanation:

The given equation is

$4x+\dfrac{1}{2}(10x-4)=6$

Using distributive property, we get

$4x+\dfrac{1}{2}(10x)+\dfrac{1}{2}(-4)=6$

$4x+5x-2=6$

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2 years ago

A boat traveled 147 miles downstream and back. The trip downstream took 7 hours. The trip back took 147 hours. Find the speed of

KonstantinChe [14]

Answer:

The speed of boat in still water is 11 miles per hour

The speed of current is 10 miles per hour .

Step-by-step explanation:

Given as :

The distance cover by boat in downstream = $d_1$ = 147 miles

The time taken by boat in downstream trip = $t_1$ = 7 hours

The distance cover by boat in upstream = $d_2$ = 147 miles

The time taken by boat in upstream trip = $t_2$ = 147 hours

Let The speed of boat in still water = $s_1$ = x mph

And The speed of the current = $s_2$ = y mph

Now, According to question

Speed = $\dfrac{\textrm Distance}{\textrm Time}$

For downstream

$s_1$ + $s_2$ = $\dfrac{d_1}{t_1}$

or, x + y = $\dfrac{147}{7}$

I.e x + y = 21 mph ..........1

For upstream

$s_1$ + $s_2$ = $\dfrac{d_2}{t_2}$

or, x - y = $\dfrac{147}{147}$

I.e x - y = 1 mph ..........2

Now, Solving Eq 1 and 2

I.e (x + y) + (x - y) = 21 + 1

Or, (x + x) + (y - y) = 22

Or, 2 x = 22

∴ x = $\frac{22}{2}$

I.e x = 11 mph

So, speed of boat = x = 11 miles per hour

Again, put The value of x in Eq 2

So, x - y = 1 mph

I.e 11 - y = 1

∴, y = 11 - 1

I.e y = 10 mph

So, speed of current = y = 10 miles per hour

Hence The speed of boat in still water is 11 miles per hour , and The speed of current is 10 miles per hour . Answer

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