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Natali [406]
2 years ago
13

About 70% of Earth’s surface is covered by water. If the diameter of Earth is about 12,750 km, find the area not covered by wate

r to the nearest 100,000 km2.
Mathematics
1 answer:
hichkok12 [17]2 years ago
4 0
Earth diameter = 12,750 km
Earth radius = 6,375 km
Sphere Surface Area     =    <span> 4 • <span>π <span>• r²
</span></span></span>Sphere Surface Area     =    4 * 3.141<span>59 * 6375^2
</span>Sphere Surface Area     =    4 * 3.14159 * <span> <span> <span> 40,640,625 </span> </span> </span>
<span> <span> <span> Earth's Entire </span></span></span><span>Surface Area     =    510,704,724 square kilometers
Surface NOT covered by water =  </span><span>510,704,724 * .3
</span>Surface NOT covered by water =  <span> <span> <span> 153,211,417</span></span></span><span> square kilometers</span>


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The area of a rectangular piece of cardboard is represented by
Liula [17]

This question is solved applying the formula of the area of the rectangle, and finding it's width. To do this, we solve a quadratic equation, and we get that the cardboard has a width of 1.5 feet.

Area of a rectangle:

The area of rectangle of length l and width w is given by:

A = wl

w(2w + 3) = 9

From this, we get that:

l = 2w + 3, A = 9

Solving a quadratic equation:

Given a second order polynomial expressed by the following equation:

ax^{2} + bx + c, a\neq0.

This polynomial has roots x_{1}, x_{2} such that ax^{2} + bx + c = a(x - x_{1})*(x - x_{2}), given by the following formulas:

x_{1} = \frac{-b + \sqrt{\Delta}}{2*a}

x_{2} = \frac{-b - \sqrt{\Delta}}{2*a}

\Delta = b^{2} - 4ac

In this question:

w(2w+3) = 9

2w^2 + 3w - 9 = 0

Thus a quadratic equation with a = 2, b = 3, c = -9

Then

\Delta = 3^2 - 4(2)(-9) = 81

w_{1} = \frac{-3 + \sqrt{81}}{2*2} = 1.5

w_{2} = \frac{-3 - \sqrt{81}}{2*2} = -3

Width is a positive measure, thus, the width of the cardboard is of 1.5 feet.

Another similar problem can be found at brainly.com/question/16995958

5 0
2 years ago
XYZ Toys makes a ec 4- Me Baby Doll for $10.40. They mark up the cost by 55%. What is the selling price for the Feed-Me Baby Dol
vladimir1956 [14]

Answer:

$16.12

Step-by-step explanation:

55% of $10.40 = 0.55 × $10.40 = $5.72

$10.40 + $5.72 = $16.12

8 0
2 years ago
What is the quotient of 5 7 ÷ 5 14 ?
KatRina [158]

Answer:

<h2><u>=</u> <u>   57 / 514  </u>    <u>(Decimal: 0.110895)</u></h2>

Step-by-step explanation:

57 / 514

<u>=   57 / 514 </u>

<u>(Decimal: 0.110895)</u>

<u></u>

<u></u>

<u></u>

<u></u>

<u></u>

<u></u>

<u></u>

<u></u>

<u></u>

<h2><u>And if that is not what you are looking for here: </u></h2><h2><u></u></h2>

Rewrite the equation as  

x /14 =  5/ 7 .  x/ 14 =  5/ 7

Multiply both sides of the equation by  

14.14  ⋅  x /14 =  14 ⋅ 5 /7

Simplify both sides of the equation.

Tap for fewer steps...

Cancel the common factor of  14 .  

Cancel the common factor.

14 ⋅  x /14 =  14 ⋅ 5 /7

Rewrite the expression.

x = 14 ⋅ 5 /7

Simplify  14 ⋅  5/ 7 .

Cancel the common factor of  7 .

Factor  7  out of  14 .

x = 7 ( 2 ) ⋅ 5/ 7

Cancel the common factor.

x = 7 ⋅  2 ⋅  5/ 7

Rewrite the expression.

x  = 2 ⋅ 5

Multiply  2  by  5 .

<u>x = 10</u>

3 0
2 years ago
Martina starting playing video games as soon as she got home from school. She played video games for 15 minutes. Then Martina he
VLD [36.1K]

Answer:

3:30PM

Step-by-step explanation:

Martina starting playing video games as soon as she got home from school. She played video games for 15 minutes. Then Martina helped clean the kitchen for 45 minutes. After the kitchen was clean, it took Martina 15 minutes to finish her homework. When Martina finished her homework, it was 4:45 P.M. What time did Martina get home from school?

Step 1

We add up the minutes it took her to do things

= Minutes for video games + Minutes for cleaning the kitchen + Minutes for doing homework

= 15 minutes + 45 minutes + 15 minutes

= 75 minutes

= 1 hour 15 minutes

Step 2

When Martina finished her homework, it was 4:45 P.M. What time did Martina get home from school?

This is calculated be subtracting 1 hour 15 minutes from 4:45 PM

= 4:45 PM - 1 : 15

= 3:30PM

Therefore, Martha got home from school by 3:30 PM

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3 years ago
A half of a number added to 7 gives 19. What is the number? *
creativ13 [48]

Answer:

24

Step-by-step explanation:

---------------

24÷2=12

12+7=19

---------------

8 0
2 years ago
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