Does anybody know how to do this?

Enny White is shopping for CDs. She decides to purchase 3 movie soundtracks. The music store has 7 different movie soundtracks i

zubka84 [21]

Answer:

$35\ ways$

Step-by-step explanation:

we know that

Combinations are a way to calculate the total outcomes of an event where order of the outcomes does not matter.

To calculate combinations, we will use the formula

$C(n,r)=\frac{n!}{r!(n-r)!}$

where

n represents the total number of items

r represents the number of items being chosen at a time.

In this problem

$n=7\\r=3$

substitute

$C(7,3)=\frac{7!}{3!(7-3)!}\\\\C(7,3)=\frac{7!}{3!(4)!}$

simplify

$C(7,3)=\frac{(7)(6)(5)4!}{3!(4)!}$

$C(7,3)=\frac{(7)(6)(5)}{3!}$

$C(7,3)=\frac{(7)(6)(5)}{(3)(2)(1)}$

$C(7,3)=35\ ways$

6 0

3 years ago

JK = 2x – 5 and KL=3x – 8 Find JL.

elena-14-01-66 [18.8K]

Answer:

where do you see jl there is only jk and kl

Step-by-step explanation:

3 0

3 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

Find three consecutive even numbers whose sum is 96?

stepladder [879]

So consectuve even numbers

we know that one even number plus 2= another even number so we want to find 3 consecutive even numbers that add up to 96 or
x is the first number
x+2 is the second number
x+4 is the third number

x+x+2+x+4=96
3x+6=96
subtract 6 from both sides
3x=90
divide both sides by 3
x=30

the first number is 30
x+2=32=second number
x+4=34=third number

the numbers are 30,32,34

3 0

3 years ago

Read 2 more answers

Factor each completely n^2 - 11n + 10

Charra [1.4K]

${n}^{2} - 11n + 10 =$

$(n - 1)(n - 10)$

.................................................

3 0

2 years ago