(PLEASE HELP PLEASE!! IM GOING TO FAIL) PLEASE HELP ME WITH THESE QUESTIONS!! NOT JUST FOR ME FOR BRAIN! WHO WILL ANSWER FIRST?!

In an endurance race, Rachel ran

Reil [10]

Answer:

$31\frac{1}{5}\ miles$

Step-by-step explanation:

we know that

The speed is equal to divide the distance by the time

so

The distance is equal to multiply the speed by the time

we have

$speed=9\frac{3}{5}\ \frac{miles}{hour}$

$time=3\frac{1}{4}\ hours$

$distance=(9\frac{3}{5})(3\frac{1}{4})$

Convert mixed number to an improper fraction

$9\frac{3}{5}=9+\frac{3}{5}=\frac{9*5+3}{5}=\frac{48}{5}$

$3\frac{1}{4}=3+\frac{1}{4}=\frac{3*4+1}{4}=\frac{13}{4}$

substitute

$distance=(\frac{48}{5})(\frac{13}{4})=\frac{624}{20}=31,2\ miles$

Convert to mixed number

$31.2\ mi=31+0.2=31+\frac{1}{5}=31\frac{1}{5}\ miles$

3 0

2 years ago

−3(x + 3) = −3(x + 1) − 5

love history [14]

You have to simplify and then get x

5 0

2 years ago

Read 2 more answers

PLEASE HELP!!!!

Artyom0805 [142]

Answer:

The total cost of producing 6 widgets is $231.

Step-by-step explanation:

5 0

2 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

2 years ago

Hello again,

Nataly [62]

Answer: 395

Step-by-step explanation:

201+99+95

5 0

2 years ago