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3 years ago

1) 5x-2y=4. 2) 3x-5y=13 x-2y=53x+y=9

1 answer:

5 0

$\left\{\begin{array}{ccc}5x-2y=4\\3x+y=9&/\cdot2\end{array}\right\\+\left\{\begin{array}{ccc}5x-2y=4\\6x+2y=18\end{array}\right\\----------\\.\ \ \ \ \ 11x=22\ \ \ \ /:11\\.\ \ \ \ \ \ \ x=2\\\\3\cdot2+y=9\\6+y=9\\y=9-6\\y=3\\\\Answer:x=2;\ y=3$

$\left\{\begin{array}{ccc}3x-5y=13\\x-2y=5\end{array}\right\\\left\{\begin{array}{ccc}3x-5y=13\\x=2y+5\end{array}\right\\\\substitute:\\\\3(2y+5)-5y=13\\6y+15-5y=13\\y=13-15\\y=-2\\\\x=2\cdot(-2)+5=-4+5=1\\\\Answer:x=1;\ y=-2.$

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34kurt

Answer:

The probability is 0.0775

The expected value is 4.75 clubs

The standard deviation is 1.8875 clubs

Step-by-step explanation:

The variable X follows a binomial distribution, because we have n identical and independent events (19 cards) with a probability p of success and 1-p of fail (there is a probability of 1/4 to be club and 3/4 to be diamond, heart or spade). Then, the probability that x of the n cards are club is:

$P(x)=\frac{n!}{x!(n-x)!}*p^{x}*(1-p)^{n-x}\\P(x)=\frac{19!}{x!(19-x)!}*0.25^{x}*(0.75)^{19-x}$

So, the probability P of drawing at least 8 clubs is:

P = P(8) + P(9) + P(10) + ... + P(18) + P(19)

Replacing, the values of x, from 8 to 19, on the equation above, we get:

P = 0.0775

Additionally, the expected value E(x) and standard deviationS(x) for this distribution is given by:

E(x)=np = 19(0.25) = 4.75

$S(x)=\sqrt{np(1-p)} =\sqrt{19(0.25)(0.75)} =1.8875$

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4 years ago

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neonofarm [45]

Answer:

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Step-by-step explanation:

To make x the subject of the formula, we basically have to isolate the x.

To do this we first multiply both sides by x.

xy=b/a

Now, to isolate the x, we simply divide by y,

x=b/(ay)

So x=b/(ay) is our answer

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3 years ago

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Answer:

Step-by-step explanation:

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