Question

posted pic

Answer 1

@primeralph

Answer 2

@mebs

Answer 3

The meaning of E(x) is the expected value in a distribution.

\[E(x) = \frac{ x }{ \mu} \]

where mew is usually the mean.

Answer 4

what is mew?

Answer 5

Its the symbol \[\mu \]

Answer 6

so ho would I plug it in to solve

Answer 7

its called the population mean right?

Answer 8

In your case its means Probability.. I think

\[0.07 = \frac{ 13 }{ \mu } \]

Answer 9

ok so then I would solve for the u right?

Answer 10

Do a few of them and see what mew is...its been a while...

Answer 11

well in my notes its a population mean.. what do u mean do a few of them

Answer 12

well there are a few to do like for 0.21 and 0.17...

Answer 13

The expected value is what you expect to get .... its not really the actual probability..

Answer 14

yea I know, I just don't understand ho id solve though.
for the one u plugged in above, id multiply 7 times the mew and then do 13 divided by that right?

Answer 15

you could try that.

Answer 16

its not on your calculator... its a generic term...you could use c or d of f or lamda..

Answer 17

yea but if I multiply that mew by 7 what would I get..

Answer 18

@gypsy1274

Answer 19

you would get 7mew... why would you do that?

Answer 20

ok. so how do I even solve for the expected value then?

Answer 21

just graph it...

Answer 22

and then???

Answer 23

it looks something like and M and they something after that

Answer 24

Alright ... Expected value is what you usually expect to come up the most right....

So you see that 21 comes up 25% of the time..

Answer 25

21??

Answer 26

for x or y?

Answer 27

im sorry I just don't understand this very much... I really don't like this unit :(

Answer 28

Just do this

E(x) = (13 * 0.07)+ (16 * 0.21) + (17*0.17)...etc

really the expected value is the variable with the most frequent occurrences.

Answer 29

I never like this unit either haha that's why I don't remember that well :P...

Answer 30

Just continue what I started at the E(x) part and tell the sum of those products.

Answer 31

ok so is this what u have to do IN ORDER TO FIND the EXPECTED VALUE???
multiply X BY p(X) AND KEEP DOING THAT AND ADD EM ALL UP????

Answer 32

yes

Answer 33

wow. :p u should've just said tht.

Answer 34

ok so when I multiply (13*0.07) + (16*0.21) + ..... i got 20.42?

Answer 35

sorry haha do you understand what expected value is though.. its not necessarily the most frequent outcome alright..

Answer 36

yea I get it. so that's how I will always frind the expected value right?

Answer 37

than that's your answer let me check
yea...

Answer 38

ok check it

Answer 39

no its different for a standard distribution and hyper geometric distribution and etc... but yea your right..

Answer 40

ok.. (and Idk what standard and geo is.. and the difference between them)

Answer 41

ok so my answer is right? k ill submit it then

Answer 42

alright fingers crossed..

Answer 43

ill tell u when its right.. but I have a quick question before that

Answer 44

what would that be?

Answer 45

if they give u a table and ask u to find the standard deviation for X, "the number that comes up on the die" how do u find it

Answer 46

\[\mu=\sum_{i=1}^{n}x _{i}p \left( x _{i} \right)\]
for discrete distributions.

Answer 47

Well the standard diviation is what pgpilot says expect the xi means

x - u

Answer 48

\[\mu=E \left( X \right)\]

Answer 49

so wait what

Answer 50

for example here's this question

Answer 51

\[VAR \left( X \right)=E \left( X ^{2} \right)-\left( E \left( X \right) \right)^{2}\] for discrete distributions and \[\sqrt{VAR \left( X \right)} = SD \left( X \right)\]