import java.io.OutputStream;
import java.io.FilenameFilter;
import java.util.Locale;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.FileInputStream;
import java.io.File;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Hieu Le
 */
public class Main {
    public static void main(String[] args) {
        Locale.setDefault(Locale.US);
        InputStream inputStream;
        try {
            final String regex = "C-(small|large).*[.]in";
            File directory = new File(".");
            File[] candidates = directory.listFiles(new FilenameFilter() {
                public boolean accept(File dir, String name) {
                    return name.matches(regex);
                }
            });
            File toRun = null;
            for (File candidate : candidates) {
                if (toRun == null || candidate.lastModified() > toRun.lastModified())
                    toRun = candidate;
            }
            inputStream = new FileInputStream(toRun);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        OutputStream outputStream;
        try {
            outputStream = new FileOutputStream("c.out");
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskC solver = new TaskC();
        int testCount = Integer.parseInt(in.next());
        for (int i = 1; i <= testCount; i++)
            solver.solve(i, in, out);
        out.close();
    }

    static class TaskC {
        private static final double EPS = 1e-7;

        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int nCores = in.nextInt();
            int target = in.nextInt();
            double units = in.nextDouble();
            double[] probs = new double[nCores];
            for (int i = 0; i < nCores; ++i)
                probs[i] = in.nextDouble();

            double low = 0.0, high = 1.0;
            for (int i = 0; i < 200; ++i) {
                double mid = (low + high) / 2;
                if (validate(probs, mid, units))
                    low = mid;
                else
                    high = mid;
            }

            double result = 1.0;
            for (double prob : probs)
                result *= Math.max(prob, low);
            out.printf("Case #%d: %.7f\n", testNumber, result);
        }

        private boolean validate(double[] probs, double floor, double units) {
            double required = 0;
            for (double p : probs) {
                if (p < floor - EPS)
                    required += floor - p;
            }
            return required - units <= EPS;
        }

    }

    static class InputReader {
        private BufferedReader reader;
        private StringTokenizer tokenizer;
        private static final int BUFFER_SIZE = 32768;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(
                    new InputStreamReader(stream), BUFFER_SIZE);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

    }
}