Question

A lottery has one $2000 prize, two $1000 prizes, and ten $500 prizes. Two thousand tickets are sold at $5 each. Find the expected value if a person buys two tickets

Answer 1

expeted value is the sum of xP(x) if i read it right

Answer 2

I got an answer of -2.80 is that correct...

Answer 3

would the probabilities be:

1/2000
2/1999
10/1997

or 2000 denoms for all of them?

Answer 4

first of all buying two tickets is a red herring.

Answer 5

easy way to do this is imagine you buy all the tickets. you spend
\[5\times \$2000=\$10,000\]

Answer 6

that should be
\[\$5\times 2000=\$10,000\] you make back
\[\$2000+2\times $1000+10\times $500=\$9000\] for a loss of $1000

Answer 7

averaged over the 2000 tickets you lost $4.5 per ticket.

Answer 8

so if you buy one ticket expected loss is -4.5, for two tickets expect to lose -9

Answer 9

we can do this using probability if you like

Answer 10

hello zarkon!

Answer 11

amistre can you please help with the other parts of the problem when you are done

Answer 12

@gfoster did you check the formula?

Answer 13

I'm not get the answer of -9

Answer 14

really? let me check my arithmetic.

Answer 15

$2,000+$2,000+10*$500=$9,000 yes?

Answer 16

First I got the answer -2.8 then I got -6 I'm not sure what I'm doing worng

Answer 17

yes that is correct

Answer 18

do you know already what the answer is?

Answer 19

No I don't - wish I did.

Answer 20

because i get an expected value of -4.5 for each ticket, unless i messed up my arithmetic. oh i thought you knew my answer was wrong. i think it is right

Answer 21

ya sorry i meant to say @satellite. the formula is correct

Answer 22

you buy all the tickets. you spend $5*2000=$10,000 yes? but you only get back $9,000 is prize money for a net loss of $1,000

Answer 23

I just didn't get the same answer that is why I'm asking

I could be wrong - I'm not very good at this :-)

Answer 24

oh ok a net loss of $1,000 averaged over the tickets. there are 2000 tickets

Answer 25

i messed up on the average. -1000/2000=-.5

Answer 26

you lose .50 per ticket

Answer 27

so expected value is -.5
if you buy two tickets expect to lose -1

Answer 28

if you buy 3 tickets expect to lose 1.5 and if you buy ten tickets expect to lose $5 etc. is it -.50 per ticket

Answer 29

okay thank you for all the help.....

Answer 30

tw

Answer 31

if it is still not clear let me know and we can do it slowly

Answer 32

sattelite those answers didnt come out right

Answer 33

really? what is the formula for Ph?