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3 years ago

Barbie is thinking of s number. Twenty less than one third of the number is 72. Find barbies number

Mathematics

2 answers:

Anvisha [2.4K]3 years ago

8 0

It is 285 because I got that one correct

bagirrra123 [75]3 years ago

7 0

if you do inverse operations you get s=285

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A rope weighs 600 grams per meter of length.What is the weight in kilograms of 12.2 meters of this rope?

Luda [366]

Answer: 7.32 kgs

Step-by-step explanation:

1m length = 600 gms = 0.6 kgs

12.2m = 12.2 x 0.6 = 7.32 kgs

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4 years ago

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55% of what number is 22?

Ilya [14]

Answer:
The number is 40

Explanation:
Assume that the number we are looking for is x.
We know that 55% of the number x is 22.
This means that:
55% of x = 22
55% * x = 22
0.55x = 22

Now, we will simply solve for x as follows:
0.55x = 22
x = $\frac{22}{0.55}$ 
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3 years ago

How do i solve for "T" in this equation: P=IRT

FromTheMoon [43]

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\frac{P}{IR}=T$

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3 years ago

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Average speed is calculated by dividing total distance with the time it takes to complete it. True False

Aliun [14]

Answer:True

Step-by-step explanation:

Average speed refers to the total distance covered in a specific time . it also a scalar quantity (has magnitude but no direction)

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4 years ago

Evaluate the surface integral:S

rjkz [21]

Assuming $S$ does not include the plane $z=0$ , we can parameterize the region in spherical coordinates using

$\mathbf r(u,v)=\left\langle3\cos u\sin v,3\sin u\sin v,3\cos v\right\rangle$

where $0\le u\le2\pi$ and $0\le v\le\dfrac\pi/2$ . We then have

$x^2+y^2=9\cos^2u\sin^2v+9\sin^2u\sin^2v=9\sin^2v$
$(x^2+y^2)=9\sin^2v(3\cos v)=27\sin^2v\cos v$

Then the surface integral is equivalent to

$\displaystyle\iint_S(x^2+y^2)z\,\mathrm dS=27\int_{u=0}^{u=2\pi}\int_{v=0}^{v=\pi/2}\sin^2v\cos v\left\|\frac{\partial\mathbf r(u,v)}{\partial u}\times \frac{\partial\mathbf r(u,v)}{\partial u}\right\|\,\mathrm dv\,\mathrm du$

We have

$\dfrac{\partial\mathbf r(u,v)}{\partial u}=\langle-3\sin u\sin v,3\cos u\sin v,0\rangle$
$\dfrac{\partial\mathbf r(u,v)}{\partial v}=\langle3\cos u\cos v,3\sin u\cos v,-3\sin v\rangle$
$\implies\dfrac{\partial\mathbf r(u,v)}{\partial u}\times\dfrac{\partial\mathbf r(u,v)}{\partial v}=\langle-9\cos u\sin^2v,-9\sin u\sin^2v,-9\cos v\sin v\rangle$
$\implies\left\|\dfrac{\partial\mathbf r(u,v)}{\partial u}\times\dfrac{\partial\mathbf r(u,v)}{\partial v}\|=9\sin v$

So the surface integral is equivalent to

$\displaystyle243\int_{u=0}^{u=2\pi}\int_{v=0}^{v=\pi/2}\sin^3v\cos v\,\mathrm dv\,\mathrm du$
$=\displaystyle486\pi\int_{v=0}^{v=\pi/2}\sin^3v\cos v\,\mathrm dv$
$=\displaystyle486\pi\int_{w=0}^{w=1}w^3\,\mathrm dw$

where $w=\sin v\implies\mathrm dw=\cos v\,\mathrm dv$ .

$=\dfrac{243}2\pi w^4\bigg|_{w=0}^{w=1}$
$=\dfrac{243}2\pi$

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3 years ago