#include<iostream>

#include<string.h>

#include<algorithm>

#include<stdio.h>

#include<math.h>

#define LL long long

using namespace std;

const int maxx = ;

const double eps = 1e-;

struct node{

   LL l,r,cnt;

   LL w;

}tree[maxx<<];

LL root[maxx];

LL a[maxx];

LL pre[maxx];

LL cnt;

LL num;

LL sumlength;

void inserts(LL l,LL r,LL pre,LL &now,LL pos){

     now=++cnt;

     tree[now]=tree[pre];

     tree[now].cnt++;

     tree[now].w=tree[now].w+pos;

     if (l==r){

        return;

     }

     LL mid=(l+r)>>;

     if (pos<=mid){

        inserts(l,mid,tree[pre].l,tree[now].l,pos);

     }else {

        inserts(mid+,r,tree[pre].r,tree[now].r,pos);

     }

}

void query(LL L,LL R,LL l,LL r,LL pos){

   // if (l>pos)return;

    if (l==r){

        num+=(tree[R].cnt-tree[L].cnt);

        sumlength+=(tree[R].w-tree[L].w);

        return ;

    }

    LL mid=(l+r)>>;

    if (pos<=mid){

       query(tree[L].l,tree[R].l,l,mid,pos);

    }else{

       num+=(tree[tree[R].l].cnt-tree[tree[L].l].cnt);

       sumlength+=(tree[tree[R].l].w-tree[tree[L].l].w);

       query(tree[L].r,tree[R].r,mid+,r,pos);

    }

}

int main(){

  LL n,q;

   while(~scanf("%lld%lld",&n,&q)){

      pre[]=;

      cnt=;

      for (int i=;i<=n;i++){

        scanf("%lld",&a[i]);

        pre[i]=pre[i-]+a[i];

        inserts(,,root[i-],root[i],a[i]);

      }

      LL ll,rr;

      LL x,y;

    while(q--){

      scanf("%lld%lld%lld%lld",&ll,&rr,&x,&y);

      double l=,r=;

      double ans=;

      while(fabs(r-l)>eps){

          double mid=(l+r)/;

          num=;

          sumlength=;

          LL ss=floor(mid);

          query(root[ll-],root[rr],,,ss);

          num=(rr-ll+)-num;

          double s=num*mid+sumlength;

          double step=1.0*(pre[rr]-pre[ll-])/y;

          if (s-step*(y-x)>eps){

            r=mid;

          }else{

            l=mid;

          }

      }

      printf("%.10f\n",l);

    }

   }

   return ;

}