diff --git a/chapter04.js b/chapter04.js
index 12f6ef0..9e43aa8 100644
--- a/chapter04.js
+++ b/chapter04.js
@@ -9,42 +9,127 @@
 
 // Problem 1: The sum of a range
 function range(start, end, step=1) {
-  // Your code here
+  var array = [];
+  var start_cpy = start;
+
+  for(var i=0; i<=(end-start); i=i+step){
+    array[i] = start_cpy;
+    start_cpy = start_cpy+1;
+  }
+  return array;
 }
 
 function sum(array) {
-  // Your code here
+  var sum = 0;
+  var old_sum = 0;
+  for(var i=0; i<range_array.length; i++){ //is there another way to cycle through elements of an array in javascript?
+    sum = range_array[i] + old_sum;
+    old_sum = range_array[i];
+  }
+  return sum;
 }
 
 // Problem 2: Reversing an Array
 function reverseArray(array) {
-  // Your code here
+  var temp_array = [];
+  for(var i=0; i<array.length; i++){
+    temp_array[(array.length)-1-i] = array[i];
+  }
+  return temp_array;
 }
 
 function reverseArrayInPlace(array) {
-  // Your code here
+  var temp;
+  for(var i=0; i<array.length; i++){
+    temp = array[i];
+    array[i] = array[(array.length)-1-i];
+  }
+  return array;
 }
 
 // Problem 3: A List
+
+/*
+List (as in linked list in C++)
+
+Objects, as generic blobs of values, can be used to build all sorts of data
+structures. A common data structure is the list (not to be confused with
+the array). A list is a nested set of objects, with the first object holding
+a reference to the second, the second to the third, and so on.
+
+var list = {
+    value : 1 ,
+    rest : {
+        value : 2,
+        rest : {
+            value : 3,
+            rest : null
+        }
+    }
+};
+*/
+
 function arrayToList(array) {
-  // Your code here
+  if(array.length === 0){
+    return null;
+  }
+
+  return{
+    value: array.shift();
+    rest: arrayToList(array);
+  }
 }
 
 function listToArray(list) {
-  // Your code here
+  var array;
+  var i = 0;
+  while(list.value != null){
+    array[i] = list.value;
+    i++;
+    list = list.rest;
+  }
+  return array;
 }
 
 function nth(list, position) {
-  // Your code here
+  if(list.value === number){
+    return true;
+  }
+  else if(list.value === null){
+    return false;
+  }
+  else{
+    return nth(number,list.rest);
+  }
 }
 
 function prepend(element, list) {
-  // Your code here
+  return{
+    value: element;
+    rest: list;
+  }
 }
 
 // Problem 4: Deep comparison
 function deepEqual(obj1, obj2) {
-  // Your code here
+  if( (typeof obj1 === typeof obj2) && typeof obj1 != "object" ){
+    if(obj1===obj2)return true;
+    else return false;
+  }
+
+  else if((typeof obj1 === typeof obj2) && typeof obj1 === object){
+    var obj1_keys = Object.keys(obj1);
+    var obj2_keys = Object.keys(obj2);
+
+    //testing to see if they have the same keys
+    for(var i=0; i<obj1_keys.length; i++){
+      var key_1 = obj1_keys[i];
+      var key_2 = obj2_keys[i];
+      if(obj1_keys[i]!=obj2_keys[i]) return false;
+      if(obj1[key_1]!=obj2[key_2]) return false;
+    }
+    return true;
+  }
 }
 
 
diff --git a/chapter05.js b/chapter05.js
index d1372cb..4e48a98 100644
--- a/chapter05.js
+++ b/chapter05.js
@@ -6,6 +6,9 @@
  *    - DO NOT modify the number of parameters for each function.
  */
 const ancestry = require('./ancestry');
+var _ = require("lodash");
+
+
 
 function average(array) {
   function plus(a, b) { return a + b; }
@@ -20,21 +23,75 @@ ancestry.forEach(function(person) {
 
 // Problem 1: Flattening
 function flatten(arrays) {
-  // Your code here
+  var reduced = _.reduce(arrays,function(concated_sofar,row){ 
+	/*concated_sofar is the running total of concatenations of arrays and row represents each array in this array of arrays */
+	/* the 1st value of concatenated_sofar is the 1st element in arrays and row is each element of arrays*/
+	return concated_sofar.concat(row);
+	})
+  return reduced;
 }
 
+
+
 // Problem 2: Mother-child age difference
 /* This must return the average age difference instead of printing it */
 function averageMomChildAgeDiff() {
-  // Your code here
+	var ancestry_array = JSON.parse(ancestry);
+
+	var age_differences = _.map(ancestry_array,function(entry){
+	  for (var i = ancestry_array.length - 1; i >= 0; i--) {
+	    if(ancestry_array[i].name === entry.mother){
+	      return entry.born - ancestry_array[i].born
+	    }
+	  }
+	});
+
+	var null_filter = _.filter(age_differences,function(entry){
+	  if(entry != null){
+	    return true;
+	  }
+	  else{
+	    return false;
+	  }
+	});
+
+	var final_avg = average(null_filter);
+	return final_avg;
 }
 
 // Problem 3: Historical life expectancy
 /* This must return the object/map with centuries as keys and average age
     for the century as the value
  */
+
 function averageAgeByCentury() {
-  // Your code here
+	var ancestry_array = JSON.parse(ancestry);
+
+	var deaths_centuries = _.map(ancestry_array,function(entry){
+	  var new_obj = {}
+	  new_obj["age_at_death"] = entry.died - entry.born;
+	  new_obj["century"] = Math.ceil(entry.died/100); //rounds up using ceiling
+	  return new_obj;
+	});
+
+	var avgs = [];
+	var output_object = {};
+	for(var i=16; i<22; i++){
+	  var ith_filter = _.filter(deaths_centuries,function(entry){
+	    if(entry["century"]===i){
+	      return true;
+	    }
+	  });
+
+	  var ith_map = _.map(ith_filter,function(entry){
+	    return entry.age_at_death;
+	  });
+
+	  var avg = average(ith_map);
+	  avgs.push(avg);
+	  output_object[i]=avg;
+	}
+	return output_object;
 }
 
 
diff --git a/chapter13.js b/chapter13.js
index ab99bc6..ca290e1 100644
--- a/chapter13.js
+++ b/chapter13.js
@@ -9,7 +9,28 @@
 
 // Problem 1: Build table
 function buildTable(data) {
-  // Your code here
+  var output = "<table>\n";
+  var properties = Object.keys(data[0]);
+  var n = properties.length;
+  
+  output += "\t<tr>\n";
+  for(var i=0; i < n; i++){
+    output += "\t\t<th>" + properties[i] + "</th>\n";
+  }
+  output += "\n\t</tr>";
+
+  for(var i=0; i<data.length; i++){
+    output+="\n\t<tr>\n";
+    var object_properties = Object.keys(data[i]);
+    var properties_end = object_properties.length;
+    for(var j=0; j<properties_end; j++){
+      output += "\t\t<td>" + (data[i][object_properties[j]]).toString() + "</td>\n";
+    }
+    output+= "\n\t</tr>";
+  }
+  output+="\n</table>";
+
+  return output;
 }