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stellarik [79]
3 years ago
8

3x+y=4 2x+y=5 solve using linear combination

Mathematics
2 answers:
Advocard [28]3 years ago
3 0
Idk what linear combination is but you can solve this way:
3x+y=4
-2x-y=-5
x=-1
3(-1)+y=4
-3+y=4
y=7
So x=-1 and y=7
BabaBlast [244]3 years ago
3 0

Answer:

(-1,7)

Step-by-step explanation:

Add the equations in order to solve for the first variable. Plug this value into the other equations in order to solve for the remaining variables.

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The heights of a random sample of 50 college students showed a mean of 174.5 centimeters and a standard deviation of 6.9 centime
Minchanka [31]

Answer:

Step-by-step explanation:

Hello!

For me, the first step to any statistics exercise is to determine what is the variable of interest and it's distribution.

In this example the variable is:

X: height of a college student. (cm)

There is no information about the variable distribution. To estimate the population mean you need a variable with at least a normal distribution since the mean is a parameter of it.

The option you have is to apply the Central Limit Theorem.

The central limit theorem states that if you have a population with probability function f(X;μ,δ²) from which a random sample of size n is selected. Then the distribution of the sample mean tends to the normal distribution with mean μ and variance δ²/n when the sample size tends to infinity.

As a rule, a sample of size greater than or equal to 30 is considered sufficient to apply the theorem and use the approximation.

The sample size in this exercise is n=50 so we can apply the theorem and approximate the distribution of the sample mean to normal:

X[bar]~~N(μ;σ2/n)

Thanks to this approximation you can use an approximation of the standard normal to calculate the confidence interval:

98% CI

1 - α: 0.98

⇒α: 0.02

α/2: 0.01

Z_{1-\alpha /2}= Z_{1-0.01}= Z_{0.99} =2.334

X[bar] ± Z_{1-\alpha /2} * \frac{S}{\sqrt{n} }

174.5 ± 2.334* \frac{6.9}{\sqrt{50} }

[172.22; 176.78]

With a confidence level of 98%, you'd expect that the true average height of college students will be contained in the interval [172.22; 176.78].

I hope it helps!

4 0
2 years ago
There are 128 students going on a field trip to pan for gold. If they are going in vans that hold 7 students each, how many vans
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128/7 is roughly 18.3 so you would need 19 vans. 18 of them would fit all 7 so you’d have 126 so the last van would fit 2 students meaning it won’t be full
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What is 4/5 divided 1/3
vova2212 [387]
The answer would be 2.4, or in fraction form 12/5. Please mark brainliest <3
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Fittoniya [83]

Answer:

Step-by-step explanation:

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171 / 7.6 = 22.5 miles per gallon

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