I need help with this ASAP please help me !

Afina-wow [57]

824 just add all the sides so 12+12+400+400=824 and in simpler form w2+l2

3 0

4 years ago

SAT scores are normed so that, in any year, the mean of the verbal or math test should be 500 and the standard deviation 100. as

vovangra [49]

Answer:

a) $P(X>625)=P(\frac{X-\mu}{\sigma}>\frac{625-\mu}{\sigma})=P(Z>\frac{625-500}{100})=P(Z>1.25)$

$P(Z>1.25)=1-P(Z$

b) $P(400$

$P(-1$

c) $z=-0.842$

And if we solve for a we got

$a=500 -0.842*100=415.8$

So the value of height that separates the bottom 20% of data from the top 80% is 415.8.

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 SAT scores of a population, and for this case we know the distribution for X is given by:

$X \sim N(500,100)$

Where $\mu=500$ and $\sigma=100$

We are interested on this probability

$P(X>625)$

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:

$P(X>625)=P(\frac{X-\mu}{\sigma}>\frac{625-\mu}{\sigma})=P(Z>\frac{625-500}{100})=P(Z>1.25)$

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

$P(Z>1.25)=1-P(Z$

Part b

We are interested on this probability

$P(400$

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:

$P(400$

And we can find this probability with this difference:

$P(-1$

And in order to find these probabilities we can find tables for the normal standard distribution, excel or a calculator.

$P(-1$

Part c

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

$P(X>a)=0.8$ (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 0.2 of the area on the left and 0.8 of the area on the right it's z=-0.842. On this case P(Z<-0.842)=0.2 and P(Z>-0.842)=0.8

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:

$z=-0.842$

And if we solve for a we got

$a=500 -0.842*100=415.8$

So the value of height that separates the bottom 20% of data from the top 80% is 415.8.

8 0

3 years ago

X² - xy = 0<br> x + y = 1

wolverine [178]

Answer:

(0, 1 ) and ( $\frac{1}{2}$ , $\frac{1}{2}$ )

Step-by-step explanation:

Given the 2 equations

x³ - xy = 0 → (1)

x + y = 1 → (2) ( subtract x from both sides )

y = 1 - x → (3)

Substitute y = 1 - x into (1)

x² - x(1 - x) = 0

x² - x + x² = 0

2x² - x = 0 ← factor out x from each term on the left side

x(2x - 1) = 0

Equate each factor to zero and solve for x

x = 0

2x - 1 = 0 ⇒ 2x = 1 ⇒ x = $\frac{1}{2}$

Substitute these values into (3) for corresponding values of y

x = 0 : y = 1 - 0 = 1 ⇒ (0, 1 )

x = $\frac{1}{2}$ : y = 1 - $\frac{1}{2}$ = $\frac{1}{2}$ ⇒ ( $\frac{1}{2}$ , $\frac{1}{2}$ )

3 0

3 years ago

Raquel and Van live in two different cities. As part of a project, they each record the lowest prices for a gallon of gas at gas

jeyben [28]

Answer:

Step-by-step explanation:

Looking at the information given, the average or mean lowest prices and standard deviations for the two cities are given. The standard deviation is a measure of variability. It is used to determine how far the values in the data are from the mean. A lower standard deviation means that the values are closer to the mean. A higher standard deviation means that the values are farther from the mean.

Since 0.07 is lower than 0.23, the correct statement that is true about their gas-price data is

Raquel's data are most likely closer to $3.42 than Van's data are to $3.78.

3 0

3 years ago

Read 2 more answers

The curve formed by a quadratic equation is called a _________

alekssr [168]

<span>The curve formed by a quadratic equation is called a PARABOLA</span>

3 0

4 years ago