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2 years ago

What is the solution of the system of equations 2x-5y=11 and -2x+3y=-9

1 answer:

6 0

Equation 1:
x = (5y+11)/2
Substitute equation 1 to 2:
-2((5y+11)/2)+ 3y=-9
-2/2 = -1 thus -1(5y+11)

Continue...
-(5y+11)+3y=-9
-5y-11+3y =-9
(-5+3)y= 11-9
-2y = 2
y=-1

Substitute y into equation 1:
x=(5*-1+11)/2
x = 6/2=3

So y=-1 and x =3

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Random samples of size 81 are taken from an infinite population whose mean and standard deviation are 200 and 18, respectively.

TiliK225 [7]

Answer:

d. 200 and 2

Step-by-step explanation:

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

In this problem, we have that:

Mean = 200

Standard deviation = 18

Sample size: 81

Standard error: $s = \frac{18}{\sqrt{81}} = 2$

So the correct answer is:

d. 200 and 2

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3 years ago

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fiasKO [112]

Answer:

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Step-by-step explanation:

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3 years ago

Brainliest + 20 points to whoever helps!!!

Darya [45]

Answer:

D. The standard deviation is known and n > 30.

Step-by-step explanation:

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2 years ago

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Evgesh-ka [11]

Answer:

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Step-by-step explanation:

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2 years ago

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Answer:

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Step-by-step explanation:

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