Evaluate 5x + 3 when x - 2<br> The value of the expression is

It is known that the life of a particular auto transmission follows a normal distribution with mean 72,000 miles and standard de

scoray [572]

Answer:

a) $P(X$

$P(z$

b) $P(X>65000)=P(\frac{X-\mu}{\sigma}>\frac{65000-\mu}{\sigma})=P(Z>\frac{65000-72000}{12000})=P(z>-0.583)$

$P(z>-0.583)=1-P(Z$

c) $P(X>100000)=P(\frac{X-\mu}{\sigma}>\frac{100000-\mu}{\sigma})=P(Z>\frac{100000-72000}{12000})=P(z>2.33)$

$P(z>2.33)=1-P(Z$

Sicne this probability just represent 1% of the data we can consider this value as unusual.

d) $z=1.28$

And if we solve for a we got

$a=72000 +1.28*12000=87360$

So the value of height that separates the bottom 90% of data from the top 10% is 87360.

Step-by-step explanation:

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".

Part a

Let X the random variable that represent the life of a particular auto transmission of a population, and for this case we know the distribution for X is given by:

$X \sim N(72000,12000)$

Where $\mu=72000$ and $\sigma=12000$

We are interested on this probability

$P(X$

And the best way to solve this problem is using the normal standard distribution and the z score given by:

$z=\frac{x-\mu}{\sigma}$

If we apply this formula to our probability we got this:

$P(X$

And we can find this probability using excel or the normal standard table and we got:

$P(z$

Part b

$P(X>65000)$

And the best way to solve this problem is using the normal standard distribution and the z score given by:

$z=\frac{x-\mu}{\sigma}$

If we apply this formula to our probability we got this:

$P(X>65000)=P(\frac{X-\mu}{\sigma}>\frac{65000-\mu}{\sigma})=P(Z>\frac{65000-72000}{12000})=P(z>-0.583)$

And we can find this probability using the complement rule and excel or the normal standard table and we got:

$P(z>-0.583)=1-P(Z$

Part c

$P(X>100000)$

And the best way to solve this problem is using the normal standard distribution and the z score given by:

$z=\frac{x-\mu}{\sigma}$

If we apply this formula to our probability we got this:

$P(X>100000)=P(\frac{X-\mu}{\sigma}>\frac{100000-\mu}{\sigma})=P(Z>\frac{100000-72000}{12000})=P(z>2.33)$

And we can find this probability using the complement rule and excel or the normal standard table and we got:

$P(z>2.33)=1-P(Z$

Sicne this probability just represent 1% of the data we can consider this value as unusual.

Part d

For this part we want to find a value a, such that we satisfy this condition:

$P(X>a)=0.1$ (a)

$P(X$ (b)

Both conditions are equivalent on this case. We can use the z score again in order to find the value a.

As we can see on the figure attached the z value that satisfy the condition with 0.9 of the area on the left and 0.1 of the area on the right it's z=1.28. On this case P(Z<1.28)=0.9 and P(z>1.28)=0.1

If we use condition (b) from previous we have this:

$P(X$

$P(z$

But we know which value of z satisfy the previous equation so then we can do this:

$z=1.28$

And if we solve for a we got

$a=72000 +1.28*12000=87360$

So the value of height that separates the bottom 90% of data from the top 10% is 87360.

5 0

3 years ago

What is the equation of the line that passes through the point (-5,5)and has a slope of -1

erastova [34]

Answer:

Step-by-step explanation:

The point-slope form of the equation is y - y₀ = m(x - x₀), where (x₀, y₀) is any point the line passes through and m is the slope:

m = -1

(-5, 5) ⇒ x₀ = -5, y₀ = 5

The point-slope form of the equation:

y - 5 = -1(x + 5)

So:

y - 5 = -x - 5 {add 5 to both sides}

y = -x ← the slope-intercept form of the equation

3 0

3 years ago

Someone please hurry and help with the two I got wrong !!!!!!!

steposvetlana [31]

Answer:

-2

35

Step-by-step explanation:

yeah-ya.........

right?

8 0

2 years ago

the average of two numbers is 34. The second number is three times the first number. What are the two numbers?

zvonat [6]

Hey!To solve this problem, we need to set up two equations and use the system of equations to solve.

Let x be the first number.
Let y be the second number.

(x + y) ÷ 2 = 34
x = 3y

Now, we can use substitution to solve.

(3y + y) ÷ 2 = 34
4y ÷ 2 = 34
2y = 34
y = 17

Now, you plug the value of y in the equation to solve for x.

x = 3*17
x = 51
hope this helps!!

8 0

3 years ago

Read 2 more answers

1. What are foci? 2. What is the first step to take to write the equation of a hyperbola? 3. How do you represent parts of a hyp

Andrei [34K]

Answer: see below

<u>Step-by-step explanation:</u>

1) Foci is plural for Focus. Since a hyperbola has two focus points, they are referred to as foci. The foci is where the sum of the distances from any point on the curve to the foci is constant.

2) When determining the equation of a hyperbola you need the following:

a) does the hyperbola open up or to the right?

b) what is the center (h, k) of the hyperbola?

c) What is the slope of the asymptotes of the hyperbola?

3) The equation of a hyperbola is:

$\dfrac{(x-h)^2}{a^2}-\dfrac{(y-k)^2}{b^2}=1\qquad or\qquad \dfrac{(y-k)^2}{b^2}-\dfrac{(x-h)^2}{a^2}=1$

(h, k) is the center of the hyperbola
± b/a is the slope of the line of the asymptotes
The equation starts with the "x" if it opens to the right and "y" if it opens up

5 0

3 years ago

Evaluate 5x + 3 when x - 2 The value of the expression is