import java.util.*;

class Main{

  public static int n;
  public static int k;
  public static double[] p;
  public static double[] np;
  public static ArrayList<Double> results;

  public static void main(String[] args) {
   In.open("public/test2.in");
        int t = In.readInt();
        for (int i = 0; i < t; i++) {
          n = In.readInt();
          k = In.readInt();
          p = new double[n];
          np = new double [n];
          for (int j = 0; j < n; j++) {
            double pj =  In.readDouble();
            if (pj == 1) {
              pj = 0.9999999;
            }
            if (pj == 0) {
              pj = 0.0000001;
            }
            p[j] = pj;
            np[j] = 1 - pj;
          }
          testCase();
          }
       In.close();
  }


  public static void testCase() {
    results = new ArrayList<Double>();
    double finalresult = 1-lessthank();
    finalresult = Math.round(1000000.0 * finalresult) / 1000000.0;
    Out.println(finalresult);
  }

  public static double lessthank(){

    // Berechnung von Arrayeintrag mit 0 Schneetagen
    double prevresult = 1;
    for (int i = 0; i < n; i++){
      prevresult = prevresult * np[i];
    }
    results.add(prevresult);


    // Berechnung  von Arraytragen mit 1 bis k-1 Schneetragen
    calculateresults(prevresult, 0, -1);

    // Aufsummieren von Wahrscheinlichkeiten von 0 bis k-1 Schneetagen
    double plessthank = 0;
    for (int i = 0; i < results.size(); i++){
      plessthank = plessthank + results.get(i);
    }
    return plessthank;
  }

  public static void calculateresults(double prevresult, int round, int change){
    if (round == k){
      return;
    }
    if (round != 0){
    prevresult = (prevresult / np[change])* p[change];
    results.add(prevresult);
    }
    change += 1;
    round += 1;
    for (int i = change; i < n; i++){
     calculateresults(prevresult, round, i);
    }
  }
}