package Main

import java.io.{FileOutputStream, FileInputStream}

import scala.io.StdIn


object Main extends App {
    Console.setIn(new FileInputStream("example.in"))

    Console.setIn(new FileInputStream("B-large-practice.in"))
    Console.setOut(new FileOutputStream("B-large-practice.out"))

    def solve(li:Int, ri:Int, ai:Array[Int]):Double = {
        Math.exp(ai.slice(li, ri + 1).map(Math.log(_)).sum / (ri - li + 1))
    }

    val cases = StdIn.readLine().toInt
    (1 to cases) foreach { n =>
        val Array(_, m) = StdIn.readLine().split(" ").map(_.toInt)
        val ai = StdIn.readLine().split(" ").map(_.toInt)
        println(s"Case #$n:")
        (1 to m) foreach ( v => {
            val Array(li, ri) = StdIn.readLine().split(" ").map(_.toInt)
            println(solve(li, ri, ai))
        })
    }
}