2 + 2 = ? This is for easy points!

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

Which of the following is the correct value for x?

dusya [7]

Answer: 56

Step-by-step explanation:

8 0

2 years ago

Read 2 more answers

4 cm on a map are equal to 6 km in real life. if two points are 16 cm apart on the map, how far apart are they in real life

Maksim231197 [3]

Answer:

24km

Step-by-step explanation:

16/4 is 4 so you multiply that by 6 and you get 24. the equation is (16/4)*6

6 0

3 years ago

Depreciation is the decrease or loss in value of an item due to age, wear, or market conditions. We usually consider

kiruha [24]

Answer:

Part A) $V(t)=-5,750t+101,250$

Part B) $\$55,250$

Step-by-step explanation:

Part A) Express the value of the bulldozer, V, as a function of how many years old it is, t.

Let

V ----> the value of the bulldozer (dependent variable or output value)

t ----> the number of years (independent variable or input value)

we know that

The linear function in slope intercept form is equal to

$V(t)=mt+b$

we have the ordered pairs

(0,101,250) and (15,15,000)

Find the slope

The formula to calculate the slope between two points is equal to

$m=\frac{y2-y1}{x2-x1}$

substitute

$m=\frac{15,000-101,250}{15-0}$

$m=-\$5,750\ per\ year$ ----> is negative because is a decreasing function

The value of b is the initial value

so

$b=\$101,250$

substitute

$V(t)=-5,750t+101,250$

Part B) The value of the bulldozer after 8 years is

For t=8 years

substitute the value of t in the linear equation

$V(t)=-5,750(8)+101,250=\$55,250$

4 0

2 years ago

Write an Equation to show how angles are are related

dusya [7]

Hello,

Answer is Alternate interior angles, as they lie on same line but in opposite direction...

Hope it helps you.. Pls mark brainliest

8 0

3 years ago