Question

Mary buys 20 tickets in a lottery that has 5000 tickets altogether. Find the probability that Mary will win
b) 2nd prize only
c) neither first nor second prize

Answer 1

You'll have a better chance of getting correct answers if this was posted on Yahoo answers

Answer 2

yeah

Answer 3

btw, the question is a little ambiguous. Mary wins by simply getting that winning ticket? or by getting the right combination of numbers?

Answer 4

how many *first* or *second" price ticket are there?

Answer 5

yes i think so, just by getting the 2nd prize ticket
and i assume there is only one

Answer 6

so there is once first price and one second price? no third, fourth and so on?

Answer 7

maybe we need more information to solve this question

Answer 8

well you're asking, so you need to tell me

Answer 9

for example, we need to know if these are the only prizes. is there a third prize

Answer 10

it might be easier if we change the question to, Mary buys 2 tickets

Answer 11

so here is how I understand it. 5000 tickets. 1 first price ticket, 1 second price ticket. The rest are losing tickets. I she bought 20 tickets. Is this what you meant?

Answer 12

yes

Answer 13

This is a dependent event. I'll work on it

Answer 14

P(2nd price) = (20C1) (1/5000) * (4998/4999) (4997/4998) * .. * (4980/4081) ≈ 0.003984797

Answer 15

P(neither 1st nor 2nd) = (4998 permute 20) / (5000 permute 20) ≈ 0.992015203

Answer 16

actually P(neither 1st or 2nd) = P( (1st and 2nd)' ) = 1 - P(1st and 2nd)
1 - (20! / (18!)) (4998 permute 18) / (5000 permute 20)
≈ 999984797

Answer 17

sorry i was away, i wish i could at this now

Answer 18

i will be sure to comment on this, when i get a chance ,

Answer 19

afk,

Answer 20

what I wasn't sure is whether "neither 1st nor 2nd" means (not 1st or not 2nd) or (not 1st and not 2nd). The two are not equivalent. I cctually did both cases

Answer 21

i believe 0.992015203 is correct