Given the following, what is the probability of choosing an purple marble and flipping tails?

the total number of living humans on arth was converted to scientific notation using an online caculation and was reported to be

gogolik [260]

7.158 * 10^9 rounds to 7 * 10^9
7 * 10^9 = 7,000,000,000

6 0

3 years ago

Rewrite the following integral in spherical coordinates.

lora16 [44]

In cylindrical coordinates, we have $r^2=x^2+y^2$ , so that

$z = \pm \sqrt{2-r^2} = \pm \sqrt{2-x^2-y^2}$

correspond to the upper and lower halves of a sphere with radius $\sqrt2$ . In spherical coordinates, this sphere is $\rho=\sqrt2$ .

$1 \le r \le \sqrt2$ means our region is between two cylinders with radius 1 and $\sqrt2$ . In spherical coordinates, the inner cylinder has equation

$x^2+y^2 = 1 \implies \rho^2\cos^2(\theta) \sin^2(\phi) + \rho^2\sin^2(\theta) \sin^2(\phi) = \rho^2 \sin^2(\phi) = 1 \\\\ \implies \rho^2 = \csc^2(\phi) \\\\ \implies \rho = \csc(\phi)$

This cylinder meets the sphere when

$x^2 + y^2 + z^2 = 1 + z^2 = 2 \implies z^2 = 1 \\\\ \implies \rho^2 \cos^2(\phi) = 1 \\\\ \implies \rho^2 = \sec^2(\phi) \\\\ \implies \rho = \sec(\phi)$

which occurs at

$\csc(\phi) = \sec(\phi) \implies \tan(\phi) = 1 \implies \phi = \dfrac\pi4+n\pi$

where $n\in\Bbb Z$ . Then $\frac\pi4\le\phi\le\frac{3\pi}4$ .

The volume element transforms to

$dx\,dy\,dz = r\,dr\,d\theta\,dz = \rho^2 \sin(\phi) \, d\rho \, d\theta \, d\phi$

Putting everything together, we have

$\displaystyle \int_0^{2\pi} \int_1^{\sqrt2} \int_{-\sqrt{2-r^2}}^{\sqrt{2-r^2}} r \, dz \, dr \, d\theta = \boxed{\int_0^{2\pi} \int_{\pi/4}^{3\pi/4} \int_{\csc(\phi)}^{\sqrt2} \rho^2 \sin(\phi) \, d\rho \, d\phi \, d\theta} = \frac{4\pi}3$

4 0

2 years ago

44 is equal to 8 times a number minus 4. what is the number?

postnew [5]

Answer:

6

Step-by-step explanation:

Let "a number" = x

44 = 8x - 4

Simplify. Isolate the variable, x. Note the equal sign, what you do to one side, you do to the other. Do the opposite of PEMDAS.

First add 4 to both sides:

44 (+4) = 8x - 4 (+4)

44 + 4 = 8x

48 = 8x

Isolate the variable, x. Divide 8 from both sides:

(48)/8 = (8x)/8

x = 48/8

x = 6

6 is your answer.

~

3 0

3 years ago

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20 POINTS

SIZIF [17.4K]

Let get all the information.
Mean:394
Deviation:35
Looking for At Least 380 feet
To find the z score you take the wanted probality subtract the mean and divide by the deviation.
z=(380-394)/35.
z=-0.4
So far so good.
But when he looked at the table he looked at probability that the home runs are less then 380 feet.
From this table
http://www.stat.ufl.edu/~athienit/Tables/Ztable.pdf
To find the answer you have to take 1-(the probability that the home runs are less than 380 feet)or 1-0.3446=0.6554
He made an error in his calculation.

8 0

3 years ago

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Zane's parents keep a chart on the wall where they mark how much Zane grows each year. When Zane was 15, he grew 3/5 of an inch

timurjin [86]

Answer:

1 1/10 or 11/10

Step-by-step explanation:

Zane grew 3/5 of an inch during the first year and 1/2 an inch during the second. First, you have to make sure the denominators are the same number. Then, add the numerators. Simplify if needed.

4 0

3 years ago

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