Lottery ticket problem (probability)

  • Context: Undergrad 
  • Thread starter Thread starter mymaydayya
  • Start date Start date
  • Tags Tags
    lottery Probability
Click For Summary

Discussion Overview

The discussion revolves around designing an instant lottery game where a player scratches off five boxes, with the goal of achieving a winning probability of approximately 0.01. The conversation includes considerations of combinatorial mathematics and the underlying probability mechanics of the game.

Discussion Character

  • Mathematical reasoning
  • Exploratory

Main Points Raised

  • One participant proposes a formula for the winning probability as (1/2)^n * (n choose 5) = 0.01, questioning its correctness.
  • Another participant suggests that to find the number of ways to choose 5 boxes from n, one should consider how many of those combinations result in a win, leading to the expression 1/(n choose 5).
  • A later reply indicates that for the probability to approximate 0.01, n choose 5 should be about 100, leading to a calculation involving the fifth root of 12000.
  • Further exploration includes testing values for n, with attempts at n = 8 and n = 9, noting the resulting combinations.
  • There is a mention of the possibility of having more marked boxes than scratched boxes, which could affect the winning probability.

Areas of Agreement / Disagreement

Participants express differing views on the correct approach to calculating the winning probability and the implications of the number of marked boxes. No consensus is reached on the best method or the specific values for n.

Contextual Notes

Participants acknowledge uncertainty regarding the game's mechanics, particularly whether players know the total number of boxes or marked boxes, which influences the probability calculations.

mymaydayya
Messages
2
Reaction score
0
An instant lottery ticket consists of a collection of boxes cpvered with gray wax. For a subset of the boxes, the gray wax hides a special mark. If a player scratches off the correct number of the marked boxes (and no boxes without mark), then that ticket is a winner, Design an instant lottery game in which a player scratches five boxes and the probability that a tickert is a winner is approximately 0.01.

---------------------------------------------------
my answer:(1/2)^n * (n choose 5) =0.01

is it right? thans~
 
Physics news on Phys.org
mymaydayya said:
An instant lottery ticket consists of a collection of boxes cpvered with gray wax. For a subset of the boxes, the gray wax hides a special mark. If a player scratches off the correct number of the marked boxes (and no boxes without mark), then that ticket is a winner, Design an instant lottery game in which a player scratches five boxes and the probability that a tickert is a winner is approximately 0.01.

---------------------------------------------------
my answer:(1/2)^n * (n choose 5) =0.01

is it right? thans~

Hi mymaydayya! Welcome to PF! :smile:

Hint: if there are n boxes, and 5 are marked, then:

how many ways are they of choosing 5 boxes?

How many of them will be winners?

Divide one by the other … :smile:
 
tiny-tim said:
Hi mymaydayya! Welcome to PF! :smile:

Hint: if there are n boxes, and 5 are marked, then:

how many ways are they of choosing 5 boxes?

How many of them will be winners?

Divide one by the other … :smile:

-----------------------------------------------------------------
how many ways are they of choosing 5 boxes? (n choose 5)

How many of them will be winners? 1

answer :1/(n choose 5)

but there is no approxite answer to 0.01

I don't know well how this game is porcessed, so I guess that players don't know how many boxes to scratch.
 
Well, you want n choose 5 to be about 100.

So you want n(n-1)(n-2)(n-3)(n-4) to be about 5! x 100, = 12000.

And the fifth root of 12000 is about 6.5.

So try n = 8, then n choose 5 = 8.7.6/1.2.3 = 56;
then try n = 9, n choose 5 = 9.8.7.6/1.2.3.4 = 126, which is nearer! :smile:

Of course, you could have a lottery in which there are 6 marked boxes, and you scratch 5 …
 

Similar threads

  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 14 ·
Replies
14
Views
2K
Replies
6
Views
8K
  • · Replies 8 ·
Replies
8
Views
3K
Replies
26
Views
49K
  • · Replies 12 ·
Replies
12
Views
6K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K