I need the answer to the below question

Hoochie [10]

The letter "x" is often used in algebra to mean a value that is not yet known. It is called a "variable" or sometimes an "unknown". In x + 2 = 7, x is a variable

8 0

3 years ago

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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

In an aquarium, there are 10 large fish and 5 small fish. Half of the large fish are red.

liraira [26]

Answer: I would think 1/3

Step-by-step explanation:

If there are 10 large fish and half are red that would mean there is a 5/10 chance of getting a red fish from the large fish.. because there are 15 fish in total you would do 5/15 because there are 15 and 10 of those fish are large and 5 of the large fish are red. And 5/15 to its simplest form is 1/3! If this is right please give brainlist!

6 0

4 years ago

If the rate of change (ROC) of the function is quadratic, what is the function type ? Choose the correct answer.

evablogger [386]

If the rate of change (ROC) of the function is quadratic, then the function type is cubic

<h3>What is rate of change?</h3>

The rate of change of a function is the rate at which the output values change over the input value

The rate of change of a function is one degree less than the actual function

This means that, a cubic function will have a quadratic rate of change

Hence, the correct option is (d)