3 years ago

Solve by elimination 5x-15y=10 3x-5y=-6

1 answer:

6 0

Multiply bottom equation by -3 to add and eliminate y’s.

So...

5x-15y=10
+-9x+15y=18

You get -4x=28 so x=-7

Plug in to get y
5(-7)-15y=10
-35-15y=10
-15y=45
So y=-3

Check in other equation
3(-7)-5(-3)=
-21+15=-6

So x= -7 and y= -3

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For X a binomial random variable with n=5 and p=1/4, answer the following

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Recall that for $X\sim\mathrm{Bin}(n,p)$ , i.e. a random variable $X$ following a binomial distribution over $n$ trials and with probability parameter $p$ ,

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So you have

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$=\dfrac{375}{1024}\approx0.37$

The expected value of $X\sim\mathrm{Bin}(n,p)$ is simply $np$ , while the standard deviation is $\sqrt{np(1-p)}$ . In this case, they are $\dfrac54=1.25$ and $\sqrt{\dfrac{15}{16}}\approx0.97$ , respectively.

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