Help with this question ??

A rock is released from rest and freely falls 70 m to the ground. What is its velocity just before impact? A. 1.2 m/s B. 7.0 m/s

Yuri [45]

Answer:

37.04 m/s

Step-by-step explanation:

we can use the equation x = x0 + v0t + 1/2at^2

a = -9.8 m/s^2, the acceleration due to gravity

x0 = 70 m, the starting point of x

v0 = 0 m/s

x = 0

this will allow us to solve for time

0 = 70 + 0 +-4.9t^2

t = 3.779

now we can use the equation v = v0 + at

v = 0 + 9.8(3.77)

v = 37.04 m/s

5 0

3 years ago

Determine whether a probability distribution is given. If a probability distribution is given, find its mean and standard deviat

drek231 [11]

Answer:

$E(X) = \sum_{i=1}^n X_i P(X_i) = 0*0.031 +1*0.156+ 2*0.313+3*0.313+ 4*0.156+ 5*0.031 = 2.5$

We can find the second moment given by:

$E(X^2) = \sum_{i=1}^n X^2_i P(X_i) = 0^2*0.031 +1^2*0.156+ 2^2*0.313+3^2*0.313+ 4^2*0.156+ 5^2*0.031 =7.496$

And we can calculate the variance with this formula:

$Var(X) =E(X^2) -[E(X)]^2 = 7.496 -(2.5)^2 = 1.246$

And the deviation is:

$Sd(X) = \sqrt{1.246}= 1.116$

Step-by-step explanation:

For this case we have the following probability distribution given:

X 0 1 2 3 4 5

P(X) 0.031 0.156 0.313 0.313 0.156 0.031

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).

We can verify that:

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

And $P(X_i) \geq 0, \forall x_i$

So then we have a probability distribution

We can calculate the expected value with the following formula:

$E(X) = \sum_{i=1}^n X_i P(X_i) = 0*0.031 +1*0.156+ 2*0.313+3*0.313+ 4*0.156+ 5*0.031 = 2.5$

We can find the second moment given by:

$E(X^2) = \sum_{i=1}^n X^2_i P(X_i) = 0^2*0.031 +1^2*0.156+ 2^2*0.313+3^2*0.313+ 4^2*0.156+ 5^2*0.031 =7.496$

And we can calculate the variance with this formula:

$Var(X) =E(X^2) -[E(X)]^2 = 7.496 -(2.5)^2 = 1.246$

And the deviation is:

$Sd(X) = \sqrt{1.246}= 1.116$

6 0

3 years ago

Anyone found this answer for this question?

Marianna [84]

Answer:

Where is the question

6 0

3 years ago

Calculate:<br> √5/2-√5+2/2+√5

klio [65]

-√5/2+√5+1
-√5/2+2√5/2+1
√5/2+1
(√5+2)/2

4 0

3 years ago

Read 2 more answers

What formula is used to show lines are parallel<br>to one another?

larisa86 [58]

Answer:

To figure out if 2 lines are parallel, compare their slopes. You can find the slope of a line by picking 2 points with XY coordinates, then put those coordinates into the formula Y2 minus Y1 divided by X2 minus X1. Calculate the slope of both lines. If they are the same, then the lines are parallel.

Step-by-step explanation:

To figure out if 2 lines are parallel, compare their slopes. You can find the slope of a line by picking 2 points with XY coordinates, then put those coordinates into the formula Y2 minus Y1 divided by X2 minus X1. Calculate the slope of both lines. If they are the same, then the lines are parallel.

3 0

3 years ago

Read 2 more answers