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3 years ago

How do I calculate percentage is a number? Ex. 30% is 15

Mathematics

2 answers:

grin007 [14]3 years ago

7 0

i learned it as "is" over "of" "per" over "cent"

cent means 100

what IS 30% OF 670

so that would be

x/670 30/100

and then you cross multiply

100x = 20100

x = 201

puteri [66]3 years ago

5 0

You first divide the number by 100 and then multiply it by the percentage that you are given

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(X^2+6x+9)/(x+2) quotient

Shalnov [3]

x+4
___________
(x+2)|(x^2+6x+9)
-x^2-2x
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4x+9
-4x-8
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so the quotient is:

(x+2)(x+4)+1/(x+2)

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2 years ago

How do I do multiplication?

levacccp [35]

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2 years ago

Read 2 more answers

Can someone help me understand this? Because I really don’t understand this at all

Otrada [13]

Answer: I believe it is A OR B

Step-by-step explanation: BECAUSE IF A⇒B AND B⇒C

THEN ¬A⇒C I THINK ITS A THO

OR ¬A⇒¬C

7 0

3 years ago

Anna and Veronica are on the opposite sides of a tower of 160 meters height. They measure the angle of elevation of the top of t

MAXImum [283]

Answer: The distance between the girls is 362.8 meters.

Step-by-step explanation:

So we have two triangle rectangles that have a cathetus in common, with a length of 160 meters.

The adjacent angle to this cathetus is 40° for Anna, then the opposite cathetus (the distance between Anna and the tower) can be obtained with the relationship:

Tan(A) = opposite cath/adjacent cath.

Tan(40°) = X/160m

Tan(40°)*160m = 134.3 m

Now, we can do the same thing for Veronica, but in this case the angle adjacent to the tower is 55°

So we have:

Tan(55°) = X/160m

Tan(55°)*160m = X = 228.5 m

And we know that the girls are in opposite sides of the tower, so the distance between the girls is equal to the sum of the distance between each girl and the tower, then the distance between the girls is:

Dist = 228.5m + 134.3m = 362.8m

8 0

2 years ago

A Norman window is a window with a semi-circle on top of regular rectangular window. (See the picture.) What should be the dimen

Vikki [24]

Answer:

bottom side (a) = 3.36 ft

lateral side (b) = 4.68 ft

Step-by-step explanation:

We have to maximize the area of the window, subject to a constraint in the perimeter of the window.

If we defined a as the bottom side, and b as the lateral side, we have the area defined as:

$A=A_r+A_c/2=a\cdot b+\dfrac{\pi r^2}{2}=ab+\dfrac{\pi}{2}\left (\dfrac{a}{2}\right)^2=ab+\dfrac{\pi a^2}{8}$

The restriction is that the perimeter have to be 12 ft at most:

$P=(a+2b)+\dfrac{\pi a}{2}=2b+a+(\dfrac{\pi}{2}) a=2b+(1+\dfrac{\pi}{2})a=12$

We can express b in function of a as:

$2b+(1+\dfrac{\pi}{2})a=12\\\\\\2b=12-(1+\dfrac{\pi}{2})a\\\\\\b=6-\left(\dfrac{1}{2}+\dfrac{\pi}{4}\right)a$

Then, the area become:

$A=ab+\dfrac{\pi a^2}{8}=a(6-\left(\dfrac{1}{2}+\dfrac{\pi}{4}\right)a)+\dfrac{\pi a^2}{8}\\\\\\A=6a-\left(\dfrac{1}{2}+\dfrac{\pi}{4}\right)a^2+\dfrac{\pi a^2}{8}\\\\\\A=6a-\left(\dfrac{1}{2}+\dfrac{\pi}{4}-\dfrac{\pi}{8}\right)a^2\\\\\\A=6a-\left(\dfrac{1}{2}+\dfrac{\pi}{8}\right)a^2$

To maximize the area, we derive and equal to zero:

$\dfrac{dA}{da}=6-2\left(\dfrac{1}{2}+\dfrac{\pi}{8}\right )a=0\\\\\\6-(1-\pi/4)a=0\\\\a=\dfrac{6}{(1+\pi/4)}\approx6/1.78\approx 3.36$

Then, b is:

$b=6-\left(\dfrac{1}{2}+\dfrac{\pi}{4}\right)a\\\\\\b=6-0.393*3.36=6-1.32\\\\b=4.68$

3 0

3 years ago