H(x)=−4.9x2+21.3x? we want to know what x is when the ball hits the ground well when the ball hits the ground the height between the ball and the ground is 0 so you want to solve for x when h(x)=0

5 0

2 years ago

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

2 years ago

What is the final amount if 865 is decreased by 16% followed by a 14% increase?

Harman [31]

Answer:

828.32

Step-by-step explanation:

865 x (1 - 0.16) x (1 + 0.14) = 828.32

6 0

2 years ago

El Sr negron tiene que redactar una serie de cartas en su oficina. A Lourdes le toma 6 horas pasar todas las cartas. A su compañ

vodka [1.7K]

El Sr negron tiene que redactar una serie de cartas en su oficina. A Lourdes le toma 6 horas pasar todas las cartas. A su compañera rosabel, le toma 9 horas en realizar la misma tarea. Si ambas trabajan juntas para hacer todo el trabajo d ela oficina,

a. Cuánto tiempo le tomará a ambas realizar el trabajo?

Answer:

3.6 horas

Step-by-step explanation:

Sea el número total de horas que ambos trabajaron = T

Deje que la cantidad total de letras por las que pasaron = 1

De la pregunta, se nos dice:

Lourdes necesitó 6 horas para revisar las cartas.

Esto significa que, cada 1 hora, Lourdes revisaba 1/6 de las letras

Rosabel tardó 9 horas en leer las letras.

Esto significa que, cada 1 hora, Rosabel revisó 1/9 de las letras

Por lo tanto,

(1/6 × 1) T + (1/9 × 1) T = 1

(1/6 + 1/9) T = 1

(3 + 2/18) T = 1

(18/5) T = 1

5T / 18 = 1

Cruz multiplicar

5T = 18

T = 18/5

T = 3.6 horas

Por lo tanto, les tomó a ambas 3.6 horas hacer el trabajo.

7 0

2 years ago