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3 years ago

What is 40% of 24 hours

Mathematics

1 answer:

V125BC [204]3 years ago

6 0

40% of 24 is 9.6 so that means it's 9.6 hours or 9 hours and 36 minutes.

You might be interested in

What is the surface area of a box with a height and width of 5 inches and a length of 8 inches ?

vodomira [7]

Answer:

210 sq in

Step-by-step explanation:

Box dimensions: 5 x 5 x 8

2 faces: 5 x 5 -> 2 * 5 * 5 = 50

4 faces: 5 x 8 -> 4 * 5 * 8 = 160

Total = 50 + 160 = 210 sq in

5 0

3 years ago

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

PLEASE HELP ME WITH THIS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Chrissy is entering a bke

slavikrds [6]

Answer:

0.80 for 0.5 mile

0.80/0.5 for 1 mile

18.5 × 0.80/0.5 for 18.5 mile

Use calculator and you answer will be 29.6

Here it is!

6 0

3 years ago

6x+4y=2 10x-8y=32 what is the exact solution by using elimination

Alexeev081 [22]

First, let's multiply the first equation by two. This is because we have to eliminate either x or y by subtraction or addition so that means either both of the x's or both of the y's in the two equations have to be equal. Thus multiplying the first equation by 2 will give 12x+8y=4.
Next, subtract equation two from equation one:
We get a third equation, 2x-0= -28
Thus, x=-28/2. x= -14
In the same way, to find y, we need to eliminate the x's in both equations. This can be done by multiplying the first equation by 5 and the second by 3
Thus : 30x+20y=10 and 30x-24y=96
Subtracting the second equation from the first, we have 0+44y=-86
y=-86/44
y = 1.96 or 43/22

6 0

4 years ago

a shadow 8 meters long is cast by a flagpole that is 15 meters tall. If a nearby fir tree is 30 meters tall, then how long will

Basile [38]

He she saidbenejw ekmeiwe idneue ie e e e e. e we e. e e e e

5 0

3 years ago