All categories

3 years ago

What is 19 x 3.564239

Mathematics

2 answers:

Phoenix [80]3 years ago

5 0

67.720541 multiply 19 by 3.564239

SSSSS [86.1K]3 years ago

5 0

19 x 3.564239=67.720541

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

Using elimination method PLEASEEEEEE IM BEGGING SOMEONE PLEASEEEEEE

hram777 [196]

What’s the question?

4 0

3 years ago

Which situation is most likely to show a constant rate of change

Firdavs [7]

Answer:

B. The amount spent on grapes compared with the weight of the purchase.

Step-by-step explanation:

A: The shoe size of a young girl compared with her age in years. For the first few years of a girl's life, her shoe size is relatively the same. When she goes through a growth spurt, her shoe size increases exponentially. So, that is not a constant rate of change.

B: The amount spent on grapes compared with the weight of the purchase. In most grocery stores, grapes are sold based on their weight, like $2.50 per pound. With each increase in 1 pound, the cost increases by $2.50. That is a constant rate of change.

C: The number of people on a city bus compared with the time of day. This value widely changes throughout the day. For example, during rush hour, there will be many people. But during times at, say, 2 to 3 AM, there will not be many people. So, this is not a constant rate of change.

D: The number of slices in a pizza compared with the time it takes to deliver it. The number of slices in a pizza never changes, so it does not depend on the time it takes to deliver. There is no rate of change.

So, B is your answer.

Hope this helps!

3 0

3 years ago

Draw the graphs of the lines below on the same grid to find the coordinates of the point of intersection. y + 5 = 2 x y = 7 − 2

Butoxors [25]

Answer:

The point of intersection is (3,1)

Step-by-step explanation:

Manipulate these equations to achieve the form of y = mx + c

1) y + 5 = 2x

Y = 2x - 5