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3 years ago

7

The average distance from the sun to venus is 67,237,910 miles. The average distance from the sun to earth is 92,955,807 miles.

What statement is true?

1 answer:

timofeeve [1]3 years ago

4 0

Both are correct, the earth is about 93 million miles away and Venus is about 67 million miles away from the sun.

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If x=6 and y=−4, evaluate the following expression:10−4xy

melomori [17]

Step-by-step explanation:

10 - 4(6) (-4)

10 - 4(-24)

10 + 96 = 106

3 0

2 years ago

Read 2 more answers

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.

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3 years ago

Which expression is equivalent to 3 sqrt (x^5y)

Marat540 [252]

Answer:

$3x^{2}\sqrt{xy}$

Step-by-step explanation:

we have

$3\sqrt{x^{5}y}$

we know that

$\sqrt{x^{5}} =\sqrt{x*x^{4}}=x^{2}\sqrt{x}$

substitute

$3\sqrt{x^{5}y}=3x^{2}\sqrt{xy}$

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2 years ago

Emily is saving up to buy a new phone. She already has $75 and can save an additional $7 per week using money from her after sch

Ipatiy [6.2K]

Answer:

$103

Step-by-step explanation:

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3 years ago

If 10 men can build a wall in 12 days , how long will it take 4 men

laila [671]

Answer:

4.8 days

Step-by-step explanation:

12/10 = 1.2

1.2 x 4 = 4.8

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1 year ago