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2 years ago

What is the product? (91-4)(-91-4)

Mathematics

2 answers:

Dovator [93]2 years ago

6 0

7569 is the answer to your question

faust18 [17]2 years ago

4 0

Answer:

7569 have a good day

Step-by-step explanation:

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What is the formula for the expected number of successes in a binomial experiment with n trials and probability of success p? C

charle [14.2K]

Answer:

$(D)E[ X ] =np.$

Step-by-step explanation:

Given a binomial experiment with n trials and probability of success p,

$f(x)=\left(\begin{array}{c}n\\k\end{array}\right)p^x(1-p)^{n-x}, 0\leq x\leq n$

$E(X)=\sum_{x=0}^{n}xf(x)= \sum_{x=0}^{n}x\left(\begin{array}{c}n\\k\end{array}\right)p^x(1-p)^{n-x}$

Since each term of the summation is multiplied by x, the value of the term corresponding to x = 0 will be 0. Therefore the expected value becomes:

$E(X)=\sum_{x=1}^{n}x\left(\begin{array}{c}n\\x\end{array}\right)p^x(1-p)^{n-x}$

Now,

$x\left(\begin{array}{c}n\\x\end{array}\right)= \frac{xn!}{x!(n-x)!}=\frac{n!}{(x-)!(n-x)!}=\frac{n(n-1)!}{(x-1)!((n-1)-(x-1))!}=n\left(\begin{array}{c}n-1\\x-1\end{array}\right)$

Substituting,

$E(X)=\sum_{x=1}^{n}n\left(\begin{array}{c}n-1\\x-1\end{array}\right)p^x(1-p)^{n-x}$

Factoring out the n and one p from the above expression:

$E(X)=np\sum_{x=1}^{n}n\left(\begin{array}{c}n-1\\x-1\end{array}\right)p^{x-1}(1-p)^{(n-1)-(x-1)}$

Representing k=x-1 in the above gives us:

$E(X)=np\sum_{k=0}^{n}n\left(\begin{array}{c}n-1\\k\end{array}\right)p^{k}(1-p)^{(n-1)-k}$

This can then be written by the Binomial Formula as:

$E[ X ] = (np) (p +(1 - p))^{n -1 }= np.$

5 0

3 years ago

*5) x—> 1 — x Help please will really appreciate it

Paha777 [63]

Hey I’m sorry but I do not know the answer.

3 0

2 years ago

Which equation represents a parabola that has a focus of (0 0) and a directrix of y = 2

Ilya [14]

The answer is 3 because z to the y a-1

3 0

3 years ago

Read 2 more answers

Evaluate 11 % of 953.23 m Give your answer rounded to 2 DP.

Akimi4 [234]

$\begin{array}{|c|ll} \cline{1-1} \textit{a\% of b}\\ \cline{1-1} \\ \left( \cfrac{a}{100} \right)\cdot b \\\\ \cline{1-1} \end{array}~\hspace{5em}\stackrel{\textit{11\% of 953.23}}{\left( \cfrac{11}{100} \right)953.23}\implies 104.86$

7 0

1 year ago

I am confusion, can someone help me?

Genrish500 [490]

450 >_ 750 - 70x

450 >_ 750 - 70x
(subtract 750 on both sides)
-300 >_ -70x
(divide by -70 to get x alone, then flip the inequality sign)
4 2/7 <_ x
(round up to 5, you can’t have 2/7 of a person)

at least 5 people have to get off

hope this helped!

3 0

2 years ago