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2 years ago

12

ASAP can somebody please tell me the steps for both problems, I will also give brainliest (please list all the steps i have to s

how my work

1 answer:

bija089 [108]2 years ago

4 0

The answer to #11 is: x = 15

The answer to #12 is: x = 5

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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

X equals 10, Y equals -2, and Z equals -5 what is x divided by y

Aleks04 [339]

X = 10
y = -2

x/y = 10/-2
x/y = -5

Hence, x/y = z

5 0

4 years ago

Read 2 more answers

The question is jimmy scores is in the bottom 25% of the scores, but he does not have the lowest score. What is one possible val

Mariulka [41]

Answer:

50% duhh

Step-by-step explanation:

25% is also a equation

4 0

3 years ago

Please helpp I'll give brainiest

Ad libitum [116K]

Answer:

bbc

bbc

ssc

Step-by-step explanation:

hahah

3 0

2 years ago

Read 2 more answers

A university is trying to determine if certain remedial classes need to be offered to their incoming class. To do so, they give

lora16 [44]

Answer:

The experiment is identifying whether a student gets less than a 75% on the entrance exam.

The trial is one exam being taken.

An outcome is a student scoring 80%.

Step-by-step explanation:

An experiment occurs when an intervention is made by a researcher and its effect are studied, thus the experiment here is identifying whether a student gets less than a 75% on the entrance exam.

The trial is the one exam being taken.

While an outcome is the aftermath of the experiment which includes a student scoring 80%.

8 0

3 years ago