What is the easiest way remember quadratics equations?

From past experience, a company has found that in carton of transistors: 92% contain no defective transistors 3% contain one def

jasenka [17]

Answer:

$E(X) = 0*0.92 + 1*0.03 +2*0.03 +3*0.02 = 0.1500$

In order to find the variance we need to find first the second moment given by:

$E(X^2) = \sum_{i=1}^n X^2_i P(X_i)$

And replacing we got:

$E(X^2) = 0^2*0.92 + 1^2*0.03 +2^2*0.03 +3^2*0.02 = 0.3300$

The variance is calculated with this formula:

$Var(X) = E(X^2) -[E(X)]^2 = 0.33 -(0.15)^2 = 0.3075$

And the standard deviation is just the square root of the variance and we got:

$Sd(X) = \sqrt{0.3075}= 0.5545$

Step-by-step explanation:

Previous concepts

The expected value of a random variable X is the n-th moment about zero of a probability density function f(x) if X is continuous, or the weighted average for a discrete probability distribution, if X is discrete.

The variance of a random variable X represent the spread of the possible values of the variable. The variance of X is written as Var(X).

Solution to the problem

LEt X the random variable who represent the number of defective transistors. For this case we have the following probability distribution for X

X 0 1 2 3

P(X) 0.92 0.03 0.03 0.02

We can calculate the expected value with the following formula:

$E(X) = \sum_{i=1}^n X_i P(X_i)$

And replacing we got:

$E(X) = 0*0.92 + 1*0.03 +2*0.03 +3*0.02 = 0.1500$

In order to find the variance we need to find first the second moment given by:

$E(X^2) = \sum_{i=1}^n X^2_i P(X_i)$

And replacing we got:

$E(X^2) = 0^2*0.92 + 1^2*0.03 +2^2*0.03 +3^2*0.02 = 0.3300$

The variance is calculated with this formula:

$Var(X) = E(X^2) -[E(X)]^2 = 0.33 -(0.15)^2 = 0.3075$

And the standard deviation is just the square root of the variance and we got:

$Sd(X) = \sqrt{0.3075}= 0.5545$

8 0

4 years ago

Mrs. Valdez wanted to determine the number of

PolarNik [594]

B

Step-by-step explanation:

8 0

4 years ago

2(z + –16) = 22 z=_______

olchik [2.2K]

First distribute the 2 through the parenthses.

So we get 2z + -32 = 22.

Since adding a negative is the same as subtracting,

we can change the problem to read 2z - 32 = 22.

Solving from here, add 32 to both sides to get 2z = 54.

Now divide both sides by 2 to get <em>z = 27</em>.

7 0

3 years ago

Read 2 more answers

Find the cubed roots of 8(cos216 + i sin216)

saw5 [17]

Step-by-step explanation:

z

3

=8(cos216

∘

+isin216

∘

)

z^3=2^3(\cos(6^3)^\circ+i\sin(6^3)^\circ)z

3

=2

3

(cos(6

3

)

∘

+isin(6

3

)

∘

)

\implies z=8^{1/3}\left(\cos\left(\dfrac{216+360k}3\right)^\circ+i\sin\left(\dfrac{216+360k}3\right)^\circ\right)⟹z=8

1/3

(cos(

3

216+360k

)

∘

+isin(

3

216+360k

)

∘

)

where k=0,1,2k=0,1,2 . So the third roots are

\begin{gathered}z=\begin{cases}2(\cos72^\circ+i\sin72^\circ)\\2(\cos192^\circ+i\sin192^\circ)\\2(\cos312^\circ+i\sin312^\circ)\end{cases}\end{gathered}

z=

⎩

⎪

⎨

⎪

⎧

2(cos72

∘

+isin72

∘

)

2(cos192

∘

+isin192

∘

)

2(cos312

∘

+isin312

∘

)

5 0

3 years ago

Pls help! marking brainliest!!

Vedmedyk [2.9K]

Answer:

x = 52

Step-by-step explanation:

∡RQS = 180 - (90 + 34)

∡RQS = 56°

∡PQS + ∡RQS = 180°

∡PQS = x + 72

x + 72 + 56 = 180

x + 128 = 180

x = 52

3 0

3 years ago