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3 years ago

Excerpt from a school newspaper:

Mathematics

2 answers:

maria [59]3 years ago

6 0

Answer:

Step-by-step explanation:

During 2008-2009 session, 20% of students were in A-B Honor Roll.

During 2009-2010, 200 out of 1000 students were in A-B Honor Roll. What's that in percentage? We divide 200 by 1000 and then multiply by 100:

$\frac{200}{1000}=0.2*100=20$

So, that's also 20%. That's the same as 2008-2009 session, so the principal is wronged!

Option A is correct: "A) There was no change in the number of students on honor roll from one year to the next."

Anika [276]3 years ago

5 0

A) There was no change in the number of students on honor roll from one year to the next. This is noticeable because 200/1000 = .2 just as 20%/100% = .2 or 20/100 = .2. So there never was a change!

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Electric charge is distributed over the disk x2 + y2 ≤ 16 so that the charge density at (x, y) is rho(x, y) = 2x + 2y + 2x2 + 2y

professor190 [17]

Answer:

Required total charge is $256\pi$ coulombs per square meter.

Step-by-step explanation:

Given electric charge is dristributed over the disk,

$x^2=y^2\leq 16$ so that the charge density at (x,y) is,

$\rho (x,y)=2x+2y+2x^2+2y^2$

To find total charge on the disk let Q be the total charge and $x=r\cos\theta,y=r\sin\theta$ so that,

$Q={\int\int}_Q\rho(x,y) dA$ where A is the surface of disk.

$=\int_{0}^{2\pi}\int_{0}^{4}(2x+2y+2x^2+2y^2)dA$

$=\int_{0}^{2\pi}\int_{0}^{4}(2r\cos\theta+2r\sin\theta+2r^2 \cos^{2}\theta+2r^2\sin^2\theta)rdrd\theta$

$=2\int_{0}^{2\pi}\int_{0}^{4}r^2(\cos\theta+\sin\theta)drd\theta+2\int_{0}^{2\pi}\int_{0}^{4}r^3drd\theta$

$=\frac{2}{3}\int_{0}^{2\pi}(\sin\theta+\cos\theta)\Big[r^3\Big]_{0}^{4}d\theta+2\int_{0}^{2\pi}\Big[\frac{r^4}{4}\Big]d\theta$

$=\frac{128}{3}\int_{0}^{2\pi}(\sin\theta+\cos\theta)d\theta+128\int_{0}^{2\pi}d\theta$

$=\frac{128}{3}\Big[\sin\theta-\cos\theta\Big]_{0}^{2\pi}+128\times 2\pi$

$=\frac{128}{3}\Big[\sin 2\pi-\cos 2\pi-\sin 0+\cos 0\Big]+256\pi$

$=256\pi$

Hence total charge is $256\pi$ coulombs per square meter.

3 0

3 years ago

3m - 12 =18 Step by step

9966 [12]

Answer:

3m=18+12

3m=30

divide both sides by 3

m=10

6 0

3 years ago

Read 2 more answers

What is a theory in science

alina1380 [7]

A scientific theory is a validated explanation of some aspect of the natural world, based on multiple facts that have been frequently verified through research and experimentation. Fact theories are not "guesses" but reliable accounts of the real world.

3 0

3 years ago

I need help pleaseeeee this is due tomorrow

sveta [45]

Another way of finding Surface Area is

SA= 2LW+2LH+2HW

L= Length

W= Width

H= Height

the answer, and explained, would be this

2. SA= 2(12)(10)+2(12)(16)+2 (10)(16)

(multiply)

3. SA= 240 + 384 + 320

(add)

The answer is..

SA=944ft3

7 0

3 years ago

A truck driver has a route that takes him 125 miles each way each day that he works. If he makes 15 roundtrips on this route per

7nadin3 [17]

Answer: 3,750 miles

Step-by-step explanation:

Route takes him 125 miles each way so in a day he travels:

= 125 + 125

= 250 miles

He made 15 roundtrips so total miles is:

= 15 * 250

= 3,750 miles

3 0

3 years ago