//The code is written. . . With 100000 random experiments, it is found that the mathematical expectation is stable at around 100000 times, at around 8.35438+0600.
//It can be considered that the mathematical expectation is 8.33 1600. Here is the code, followed by the answer.
# include & ltstdio.h & gt
# include & ltstring.h & gt
# include & lttime.h & gt
//This code is in C language. To become C++, just use the following two lines of code.
# include & ltiostream & gt
Use namespace std
int main()
{
int times[5]；
Int mark;
Internal temperature;
Int count;
int I；
int sum
char c；
int k = 0；
int n = 100000；
Srand ((unsigned) (time(NULL)))；);
sum = 0；
Printf ("How many randomized trials have been conducted? \ n ")；
n = 100000；
while( scanf("%d "，& ampn)& amp； & ampn & gt0 )
{
while( n -)
{
k++；
Flag^= national flag;
memset(times，0，sizeof(times))；
And (flag! = 0x 1E)
{
temp = rand()% 4+ 1；
flag | =( 1 & lt； & lttemp)；
times[temp]++；
}
Count = 0;
for(I = 1； I < = 4; i++)
{
Counts += multiplied by [I];
}
Sum+= count;
Printf ("The total number of trips to McDonald's during the collection of %d ABCD is X = %d\n", k, counts);
Printf ("mathematical expectation EX = %lf \n", k, (double)sum/k is obtained from the total number of times of collecting ABCD in the first %d times);
}
}
getchar()；
Returns 0;
}
/*
How many randomized trials have been conducted? 100000
The total number of trips to McDonald's in the 1 ABCD set is X = 9.
The mathematical expectation EX = 9 is obtained from the total number of times ABCD is collected at 1.
The total number of trips to McDonald's in the second episode of ABCD is X = 8.
The mathematical expectation EX = 8.500000 is obtained from the total number of times of collecting ABCD in the previous two times.
.
.
.
.
.
.
The total number of trips to McDonald's in the 99989th ABCD collection is X = 6.
The mathematical expectation ex = 8.35438+0756 is obtained from the total number of times when ABCD was collected for the 99989th time.
The total number of trips to McDonald's in the 99990th ABCD collection is X = 4.
The mathematical expectation ex = 8.3 17 13 is derived from the total number of 99990 collections before ABCD.
The total number of trips to McDonald's in the 9999 1 collection of ABCD is X = 6.
The mathematical expectation ex = 8.399 1690 is obtained from the total number of times of collecting ABCD at 9999 1.
The total number of trips to McDonald's in 99992 ABCD collection is X = 5.
The mathematical expectation ex = 8.35438+0657 is obtained from the total number of times when ABCD was collected for the 99992nd time.
The total number of trips to McDonald's in 99993 ABCD set is X = 8.
The mathematical expectation ex = 8.35438+0653 is obtained from the total number of times when ABCD was collected for the 99993rd time.
The total number of trips to McDonald's in 99994 ABCD set is X = 6.
The mathematical expectation ex = 8.35438+0630 is obtained from the total number of times when ABCD was collected for the 99994th time.
The total number of trips to McDonald's in the 99995 ABCD collection is X = 6.
The mathematical expectation ex = 8.35438+0607 is obtained from the total number of times when ABCD was collected for the 99995th time.
The total number of trips to McDonald's in 99996 ABCD set is X = 7.
The mathematical expectation ex = 8.35438+0593 is obtained from the total number of times when ABCD was collected for the 99996th time.
The total number of trips to McDonald's in the 99997th ABCD collection is X = 9.
The mathematical expectation ex = 8.3 1600 is obtained from the total number of times when ABCD was collected for the 99997th time.
The total number of trips to McDonald's in 99998 ABCD collection is X = 9.
The mathematical expectation ex = 8.35438+0607 is obtained from the total number of ABCD collections in the first 99998 times.
The total number of trips to McDonald's in 99999 ABCD set is X = 15.
The mathematical expectation ex = 8.35438+0673 is obtained from the total number of ABCD collections in the first 99999 times.
The total number of trips to McDonald's in the100000th ABCD set is X = 13.
The mathematical expectation ex = 8.438+000000 is obtained from the total number of times of collecting ABCD10000th.
*/
//finally stabilized around 8.33 1600.
//It can be considered that the mathematical expectation is 8.33 1600.