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3 years ago

1. A rectangle has an area of 12 m2 and a width

Mathematics

1 answer:

adelina 88 [10]3 years ago

8 0

Answer:

L = 3 cm

Step-by-step explanation:

let lenght be L

First convert area in cm

1 m = 100 cm

12 m = 1200 cm

Area of rectangle = width x lenght

1200 cm = 400 cm x L

1200 /400 = L

3 cm = L

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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:

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

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4 years ago

5. Bill is planning to paint the back of his house. If the paint costs $2 a square

USPshnik [31]

Answer:

$462.86

Step-by-step explanation:

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3 years ago

Reduce 12/20 to lowest term

skelet666 [1.2K]

Answer:

3/5

Step-by-step explanation:

12/20

(divide both by 2)

12/2= 6

20/2=10

6/10

(divide by both by 2)

6/2= 3

10/2= 5

3/5

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3 years ago

How many times larger is 2 x 1012 than 5 x 106?

vfiekz [6]

Answer: It is 3.81886792453 times larger

Step-by-step explanation: 2 x 1012 is 2024

5 x 106 is 530

so take 2024 and divide it by 530 and you get 3.81886792453

in case you were wondering this rounds to 3.82

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6 0

3 years ago

Type your answer and then click or tap Done.

masya89 [10]

Answer:

See below

Step-by-step explanation:

x(x-2y)-(y-x)2

Final result :

-y2

Step by step solution :

Step 1 :

Equation at the end of step 1 :

x • (x - 2y) - (y - x)2

Step 2 :

2.1 Evaluate : (y-x)2 = y2-2xy+x2

Final result :

-y2

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2 years ago