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2 years ago

How many lines of symmetry does this polygon have?

Mathematics

1 answer:

Iteru [2.4K]2 years ago

7 0

Answer:

I believe there are only 5...

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There were some people on a train 18 people get off at the first stop and 21 people get on the train there are now 65 people on

MissTica

Answer:

Step-by-step explanation:

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3 years ago

Find the surface area of the regular pentagonal pyramid.

mr_godi [17]

Area of each side triangle is 1/2*8*15 = 60. There are 5 of them so the triangles have surface area 300. the pentagon's area 1/2*apothegm*sidelength*sides = 1/2*5.5*8*5 = 110. The total area is therefore 300+110 = 410

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2 years ago

What is the equation of the graphed line written in standard form?

Dmitry_Shevchenko [17]

Answer:

Step-by-step explanation:

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3 years ago

Find the mean, variance &a standard deviation of the binomial distribution with the given values of n and p.

MrMuchimi

A random variable following a binomial distribution over $n$ trials with success probability $p$ has PMF

$f_X(x)=\dbinom nxp^x(1-p)^{n-x}$

Because it's a proper probability distribution, you know that the sum of all the probabilities over the distribution's support must be 1, i.e.

$\displaystyle\sum_xf_X(x)=\sum_{x=0}^n\binom nxp^x(1-p)^{n-x}=1$

The mean is given by the expected value of the distribution,

$\mathbb E(X)=\displaystyle\sum_xf_X(x)=\sum_{x=0}^nx\binom nxp^x(1-p)^{n-x}$
$\mathbb E(X)=\displaystyle\sum_{x=1}^nx\frac{n!}{x!(n-x)!}p^x(1-p)^{n-x}$
$\mathbb E(X)=\displaystyle\sum_{x=1}^n\frac{n!}{(x-1)!(n-x)!}p^x(1-p)^{n-x}$
$\mathbb E(X)=\displaystyle np\sum_{x=1}^n\frac{(n-1)!}{(x-1)!((n-1)-(x-1))!}p^{x-1}(1-p)^{(n-1)-(x-1)}$
$\mathbb E(X)=\displaystyle np\sum_{x=0}^n\frac{(n-1)!}{x!((n-1)-x)!}p^x(1-p)^{(n-1)-x}$
$\mathbb E(X)=\displaystyle np\sum_{x=0}^n\binom{n-1}xp^x(1-p)^{(n-1)-x}$
$\mathbb E(X)=\displaystyle np\sum_{x=0}^{n-1}\binom{n-1}xp^x(1-p)^{(n-1)-x}$

The remaining sum has a summand which is the PMF of yet another binomial distribution with $n-1$ trials and the same success probability, so the sum is 1 and you're left with

$\mathbb E(x)=np=126\times0.27=34.02$

You can similarly derive the variance by computing $\mathbb V(X)=\mathbb E(X^2)-\mathbb E(X)^2$ , but I'll leave that as an exercise for you. You would find that $\mathbb V(X)=np(1-p)$ , so the variance here would be

$\mathbb V(X)=125\times0.27\times0.73=24.8346$

The standard deviation is just the square root of the variance, which is

$\sqrt{\mathbb V(X)}=\sqrt{24.3846}\approx4.9834$

7 0

3 years ago

New math question!<br> (screenshot attached)

Lyrx [107]

Answer:

Step-by-step explanation:

hi again

because the cornets show that -4 and -2 are also by -4 and -6 so that would =x+1 and x-5

hope this helps have a good day

love, The chris mac

3 0

2 years ago

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