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2 years ago

10

Pls hurry I’m being

1 answer:

kati45 [8]2 years ago

7 0

D. Warm air rises and cool air sinks

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What is 2792 + 9383790202

AlladinOne [14]

Answer:

9383792994

Step-by-step explanation:

I the answer is 9383792994

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2 years ago

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How to turn 3/9 in to a decimal ? no calculator

Lady_Fox [76]

3/9 reduces to 1/3 (divide both parts by the GCF 3)

Then use long division to divide 1/3

See attached of what I mean

Which is why $\frac{1}{3} \approx 0.3333$

The '3's in 0.333 will go on forever

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2 years ago

What is the median of the lower half of the data 5,8,10,1,7,6,15,8,6

Degger [83]

I’m think it is the median

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3 years ago

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Can someone solve number 32?

MaRussiya [10]

This one above lol ,......................m

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3 years ago

4. A random variable X has a mean of 10 and a standard deviation of 3. If 2 is added to each value of X, what will the new mean

Ede4ka [16]

Adding 2 to each value of the random variable $X$ makes a new random variable $X+2$ . Its mean would be

$E[X+2]=E[X]+E[2]=E[X]+2$

since expectation is linear, and the expected value of a constant is that constant. $E[X]$ is the mean of $X$ , so the new mean would be

$E[X+2]=10+2=12$

The variance of a random variable $X$ is

$V[X]=E[X^2]-E[X]^2$

so the variance of $X+2$ would be

$V[X+2]=E[(X+2)^2]-E[X+2]^2$

We already know $E[X+2]=12$ , so simplifying above, we get

$V[X+2]=E[X^2+4X+4]-12^2$

$V[X+2]=E[X^2]+4E[X]+4-12^2$

$V[X+2]=(V[X]+E[X]^2)+4E[X]-140$

Standard deviation is the square root of variance, so $V[X]=3^2=9$ .

$\implies V[X+2]=(9+10^2)+4(10)-140=9$

so the standard deviation remains unchanged at 3.

NB: More generally, the variance of $aX+b$ for $a,b\in\mathbb R$ is

$V[aX+b]=a^2V[X]+b^2V[1]$

but the variance of a constant is 0. In this case, $a=1$ , so we're left with $V[X+2]=V[X]$ , as expected.

5 0

3 years ago