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3 years ago

If the sphere shown above has a radius of 17 units, then what is the approximate volume of the sphere?

Mathematics

1 answer:

ExtremeBDS [4]3 years ago

3 0

Answer:

Approximately 20,579 units.

You might be interested in

5.3, CD r- 8.8, and AD - 14.3, find AB to the nearest tenth. If BC

pychu [463]

5.3/8.8=x/14.3
AB is x,
x= 2.43

Hope I helped.

7 0

3 years ago

Suppose that W1, W2, and W3 are independent uniform random variables with the following distributions: Wi ~ Uni(0,10*i). What is

nadya68 [22]

I'll leave the computation via R to you. The $W_i$ are distributed uniformly on the intervals $[0,10i]$ , so that

$f_{W_i}(w)=\begin{cases}\dfrac1{10i}&\text{for }0\le w\le10i\\\\0&\text{otherwise}\end{cases}$

each with mean/expectation

$E[W_i]=\displaystyle\int_{-\infty}^\infty wf_{W_i}(w)\,\mathrm dw=\int_0^{10i}\frac w{10i}\,\mathrm dw=5i$

and variance

$\mathrm{Var}[W_i]=E[(W_i-E[W_i])^2]=E[{W_i}^2]-E[W_i]^2$

We have

$E[{W_i}^2]=\displaystyle\int_{-\infty}^\infty w^2f_{W_i}(w)\,\mathrm dw=\int_0^{10i}\frac{w^2}{10i}\,\mathrm dw=\frac{100i^2}3$

so that

$\mathrm{Var}[W_i]=\dfrac{25i^2}3$

Now,

$E[W_1+W_2+W_3]=E[W_1]+E[W_2]+E[W_3]=5+10+15=30$

and

$\mathrm{Var}[W_1+W_2+W_3]=E\left[\big((W_1+W_2+W_3)-E[W_1+W_2+W_3]\big)^2\right]$

$\mathrm{Var}[W_1+W_2+W_3]=E[(W_1+W_2+W_3)^2]-E[W_1+W_2+W_3]^2$

We have

$(W_1+W_2+W_3)^2={W_1}^2+{W_2}^2+{W_3}^2+2(W_1W_2+W_1W_3+W_2W_3)$

$E[(W_1+W_2+W_3)^2]$

$=E[{W_1}^2]+E[{W_2}^2]+E[{W_3}^2]+2(E[W_1]E[W_2]+E[W_1]E[W_3]+E[W_2]E[W_3])$

because $W_i$ and $W_j$ are independent when $i\neq j$ , and so

$E[(W_1+W_2+W_3)^2]=\dfrac{100}3+\dfrac{400}3+300+2(50+75+150)=\dfrac{3050}3$

giving a variance of

$\mathrm{Var}[W_1+W_2+W_3]=\dfrac{3050}3-30^2=\dfrac{350}3$

and so the standard deviation is $\sqrt{\dfrac{350}3}\approx\boxed{116.67}$

# # #

A faster way, assuming you know the variance of a linear combination of independent random variables, is to compute

$\mathrm{Var}[W_1+W_2+W_3]$

$=\mathrm{Var}[W_1]+\mathrm{Var}[W_2]+\mathrm{Var}[W_3]+2(\mathrm{Cov}[W_1,W_2]+\mathrm{Cov}[W_1,W_3]+\mathrm{Cov}[W_2,W_3])$

and since the $W_i$ are independent, each covariance is 0. Then

$\mathrm{Var}[W_1+W_2+W_3]=\mathrm{Var}[W_1]+\mathrm{Var}[W_2]+\mathrm{Var}[W_3]$

$\mathrm{Var}[W_1+W_2+W_3]=\dfrac{25}3+\dfrac{100}3+75=\dfrac{350}3$

and take the square root to get the standard deviation.

8 0

3 years ago

How to you get the radical form?

Over [174]

Answer:

Note: this answer is kind of long so jump to picture to see a visual process.

In order to find the simplest radical form of a square root, you need prime factorize the number. In order to do this, you take a number and divide it by different prime numbers until all of its factors are now prime. We will use 24 as our example. 24 divided by 2 (which is prime) is 12. 12 divided by 2, is 6. 6 divided by 2 is 3. Therefor, our prime factorization of 24 is 2^3 * 3, which basically means 8 * 3. Then, take take out pairs of the same number and put on the OUTSIDE of the root. However, make sure that it is NEXT to the square root and not inside the mini hook that the square root makes. This means that that number is multiplying the square root of the number. Now, the only pair in this prime factorization is 2, so take two out of the prime factorization and that leaves us with square root 6 times 2, which is the answer.

Also, when taking out pairs, only take one number from the pair (in this case 2) and put it on the outside. If there is another pair, multiply that number by the other number. So if there was a pair of 3 and a pair of 2, take out 1 three and 1 two and multiply them and put on the outside.

Step-by-step explanation:

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5 0

2 years ago

Sort the measurements from least to greatest.

Nookie1986 [14]

Answer:

48 fl oz

3 1/2 pt

1/2 gal

1 1/4 qt

10 3/4c

Step-by-step explanation:

its easier if you covert each of them into the same unit such a gallons, that way you can compare them side by side

8 0

3 years ago

PUZZLE #2

Maksim231197 [3]

I have no clue I don’t understand this

4 0

2 years ago