[Homework]Packet switching versus circuit switching

Following is the key in detail, i just implemented it in java:

import java.text.DecimalFormat;public class test {public static void main(String[] args) {double sumP = 0.0;for (int i = 11; i <= 35; i++) {sumP += getCombination(i, 35)*Math.pow(0.1,i)*Math.pow(0.9, 35-i);}DecimalFormat df = new DecimalFormat("#.0000000");String fP = df.format(sumP);System.out.println(fP);}public static double getCombination(int r, int n){return doFactorial(n)/(doFactorial(r)*doFactorial(n-r));}public static double doFactorial(int n){if(n<0){return -1;}else if(n==0){return 1;}else if(n==1){return 1;}else{return n*doFactorial(n-1);}}}

the result is 0.0004243