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3 years ago

Consider function f. f(x) = sqrt 7x- 21

Mathematics

2 answers:

Arada [10]3 years ago

6 0

Answer:

f^-1(x) = (x² + 21)/7

Step-by-step explanation:

Since f(x) = y = √(7x – 21), to find the inverse of f(x) we have to write x in terms of y in order to make x the dependent variable and y the independent variable. The steps involved are:

Step 1: square both sides of the equation, y = √(7x – 21). Doing that, we have:

y² = 7x – 21

Step 2: Add 21 to both sides of the resulting equation. Doing that, we have:

y² + 21 = 7x

Step 3: Divide both sides of the equation by 7. Doing that we have:

x = (y² + 21)/7

Step 4: Replace x with f^-1(x) and y with x. Doing that, we have:

f^-1(x) = (x² + 21)/7

kipiarov [429]3 years ago

4 0

Answer:look at explanation

Step-by-step explanation:

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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

Can someone help me with #s 16 18 19 20 I WILL GIVE BRAINLIEST

Masteriza [31]

Answers & Step-by-step explanation:

<h2>PEMDAS (Parenthesis, exponents, multiplication, division, addition, subtraction)</h2>

Now let's solve your problems!

First, we see if there are any parentheses. Since there are no parentheses, we will evaluate the exponent 3² first.

After this, our problem now looks like this:

Next, since multiplication (not subtraction) is next on the list, we will evaluate 6 × 3, which equals 18.

After that, we will subtract:

41 - 9 = 32

18 - 26 = -8

We now have 32/-8 or 4/-1 or simply -4.

<h2>The answer is: -4</h2><h2>___________________________________________________</h2><h2>17.</h2>

With this, one, note the parentheses. This means that we will do these operations first.

(21 - 4²) = 5

(3 + 1) = 4

The problem now looks like this:

$\frac{5 * 4}{8^{2}-44}$

Next, we do the exponents:

8² = 64

After that, we do the multiplication of 5 x 4, which equals 20.

We now have 20/64 - 44, which simplifies to 20/20 or 1/1 or 1.

<h2>The answer is: 1</h2><h2>___________________________________________________</h2><h2>18.</h2>

Again, we see parentheses, so that means we need to do these operations first.

(6² - 20) = 16

We now have:

48 ÷ 16 + 5

48/16 = 3 and 3 + 5 = 8

<h2>The answer is: 8</h2><h2>___________________________________________________</h2><h2>19.</h2>

Here, we see an exponent 3³, so we'll need to evaluate this first.

3³ = 27

We now have:

4 × 27 ÷ 18 + 14

4 × 27 = 108

108/18 = 6

And finally:

6 + 14 = 20

<h2>The answer is: 20</h2><h2>___________________________________________________</h2><h2>20.</h2>

Here we again see the parentheses, which means we need to evaluate the subtraction first.

3 - 8 = -5

We now have:

11 + 2 (-5)

2 × -5 = -10

11 + -10 (same as 11 - 10) = 1

<h2>The answer is: 1</h2><h2>___________________________________________________</h2><h2><em>I AM ALWAYS HAPPY TO HELP :)</em></h2>

7 0

3 years ago

Please help me solve 8x+2y=32 and 10x-5y=-20

Tju [1.3M]

Answer:

(2,8)

x = 2

y = 8

Step-by-step explanation:

<u>The steps are shown in the picture</u>

7 0

3 years ago

What is the value of y?

julsineya [31]

Check the picture below.

make sure your calculator is in Degree mode.

3 0

3 years ago

Read 2 more answers

On a farm in iowa lived grandpa bill in a big yellow house on the top of the hill. His 70th birthday was this very day. All of h

DENIUS [597]

Let g be the number of grandchildren, and d be the number of dogs. They both have only one head, so the number of heads is

$g+d=33$

Grandchildren have 2 legs, while dogs have 4. So, the total number of legs is

$2g+4d=84$

From the first equation (the one for the heads) we can derive

$g=33-d$

Substitute this into the second to get

$2g+4d=84 \implies 2(33-d)+4d=84 \iff 2d=18 \iff d=9$

So, there are 9 dogs and (from the first equation

$g=33-9=24$

8 0

3 years ago