All categories

3 years ago

NEED HELP FAST!

Mathematics

1 answer:

saveliy_v [14]3 years ago

8 0

That is a 45 45 90 triangle.The hypotenuse of such a triangle equals one of the legs multiplied by the square root of 2.300 * sq root (2)=300 * <span> <span> <span> 1.4142135624 </span> </span> </span> Distance "D" = 300 * <span> <span> 1.4142135624 </span> </span>Distance "D" = <span> <span> <span> 424.3 meters
</span></span></span>(rounded to the nearest 10th of a meter.
<span> </span>
Source:http://www.1728.org/trig2.htm

You might be interested in

A building has n floors numbered 1,2,...,n, plus a ground floor g. at the ground floor, m people get on the elevator together, a

fomenos

Let $X_i$ be the random variable indicating whether the elevator does not stop at floor $i$ , with

$X_i=\begin{cases}1&\text{if the elevator does not stop at floor }i\\0&\text{otherwise}\end{cases}$

Let $Y$ be the random variable representing the number of floors at which the elevator does not stop. Then

$Y=X_1+X_2+\cdots+X_{n-1}+X_n$

We want to find $\mathrm{Var}(Y)$ . By definition,

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

As stated in the question, there is a $\dfrac1n$ probability that any one person will get off at floor $n$ (here, $n$ refers to any of the $n$ total floors, not just the top floor). Then the probability that a person will not get off at floor $n$ is $1-\dfrac1n$ . There are $m$ people in the elevator, so the probability that not a single one gets off at floor $n$ is $\left(1-\dfrac1n\right)^m$ .

So,

$\mathbb P(X_i=x)\begin{cases}\left(1-\dfrac1n\right)^m&\text{for }x=1\\\\1-\left(1-\dfrac1n\right)^m&\text{for }x=0\end{cases}$

which means

$\mathbb E[Y]=\mathbb E\left[\displaystyle\sum_{i=1}^nX_i\right]=\displaystyle\sum_{i=1}^n\mathbb E[X_i]=\sum_{i=1}^n\left(1\cdot\left(1-\dfrac1n\right)^m+0\cdot\left(1-\left(1-\dfrac1n\right)^m\right)$
$\implies\mathbb E[Y]=n\left(1-\dfrac1n\right)^m$

and

$\mathbb E[Y^2]=\mathbb E\left[\left(\displaystyle\sum_{i=1}^n{X_i}\right)^2\right]=\mathbb E\left[\displaystyle\sum_{i=1}^n{X_i}^2+2\sum_{1\le i$

Computing $\mathbb E[{X_i}^2]$ is trivial since it's the same as $\mathbb E[X_i]$ . (Do you see why?)

Next, we want to find the expected value of the following random variable, when $i\neq j$ :

$X_iX_j=\begin{cases}1&\text{if }X_i=1\text{ and }X_j=1\\0&\text{otherwise}\end{cases}$

If $X_iX_j=0$ , we don't care; when we compute $\mathbb E[X_iX_j]$ , the contributing terms will vanish. We only want to see what happens when both floors are not visited.

$\mathbb P(X_iX_j=1)=\left(1-\dfrac2n\right)^m$
$\implies\mathbb E[X_iX_j]=\left(1-\dfrac2n\right)^m$
$\implies2\displaystyle\sum_{1\le i$

where we multiply by $n(n-1)$ because that's how many ways there are of choosing indices $i,j$ for $X_iX_j$ such that $1\le i$ .

So,

$\mathrm{Var}[Y]=n\left(1-\dfrac1n\right)^m+2n(n-1)\left(1-\dfrac2n\right)^m-n^2\left(1-\dfrac1n\right)^{2m}$

4 0

3 years ago

Tim answered all the question on his math test but got 10 answers wrong. He received 4 points for every correct answer, and ther

Alex17521 [72]

76 ÷4=19

76/4+10=x

19+10=x

29=x

There is 29 questions on the test, and he got 19 correct. (65.5%)

good luck

5 0

3 years ago

To build a computer, you need to buy a motherboard for 120 dollars, a CPU for

Alborosie

Answer:

Your answer is correct. Good job!

Step-by-step explanation:

6 0

3 years ago

Evaluate the function rule below when x= -2<br><br> F(x)=3x+2

garri49 [273]

<h2>Answer:</h2><h2>-4</h2><h2 /><h2>Step-by-step explanation:</h2><h2>3 · -2 = -6</h2><h2 /><h2>-6 + 2</h2><h2 /><h2 /><h2>= -4</h2>

<h2><u>Final Anwer = -4</u></h2><h2><u /></h2><h2 /><h2>Hope this helps!! ♥︎</h2>

4 0

3 years ago

What is x for the equation 4x^2-12x=7 <br> (Only one variable for x)

VARVARA [1.3K]

Answer:

x=-1/2, 7/2

Step-by-step explanation:

move all terms to the left side and set them equal to zero. then set eac factor to zero

3 0

3 years ago

Read 2 more answers