What is the smallest number of tosses for all outcomes?

66 Views Asked by At

What is the smallest number of tosses that need to be done to get all the possible outcomes $\{1, 2, 3, 4, 5,6\}$ of a right dice with a reliability of $0.99$?

My attempt is to use the Bernoulli scheme and the Moivre–Laplace theorem: $$P\left(\left|\frac{\mu}{n}-p\right|<\delta\right)=2\Phi\left(\delta \sqrt{\frac{n}{p \cdot q}}\right)=0.99$$ but I don't know how to define $\delta$ here.

2

There are 2 best solutions below

0
On BEST ANSWER

you want to calculate the probability that 6 events all happen. This can be done with inclusion exclusion.

We get $\sum\limits_{i=0}^6 \binom{6}{i} (-1)^i (\frac{i}{6})^N$ which we can approximate from above as $1-6(5/6)^N$ so we are going to require $6(\frac{5}{6})^N < 1/100$. we can solve for $N$ and we get $N=\frac{-log(600)}{log(5)-log(6)}$ which is approximately $35.086$, so if I had to guess I would say $35$ is the first value, although apparently I got it wrong and it's $36$, but to be fair with $35$ you get approximately $0.9898$. Unless there is something wrong with my code (which I include next).

#include<bits/stdc++.h>
using namespace std;

const int MAX = 15;
int bino[MAX][MAX];

long double pot(long double b,int e){
        long double res = 1;
        while(e){
                if( e%2) res = res*b;
                b = b*b;
                e/=2;
        }
        return res;
}

int main(){
        int n;
        cin >> n;
        for(int i=0;i<MAX;i++){
                bino[i][0] = 1;
        }
        for(int i=1;i<MAX;i++){
                for(int j=1;j<MAX;j++){
                        bino[i][j] = bino[i-1][j] + bino[i-1][j-1];
                }
        }
        long double res = 0;
        for(int i = 0;i<=6;i++){
                long double summand = 1;
                summand = summand*bino[6][i];
                summand = summand*pot(-1,i);
                summand = summand*pot((1.0/6)*i,n);
                res += summand;
        }
        cout << res << endl;


}
3
On

The probability that at least one number does not appear after n tosses is $Q=6(\frac{5}{6})^n-15(\frac{4}{6})^n+20(\frac{3}{6})^n-15(\frac{2}{6})^n+6(\frac{1}{6})^n$, so the desire probability is $P=1-Q$. Solve for $n$ with $Q=0.01$