diff --git a/src/main/java/rocks/zipcode/quiz4/arrays/ArrayUtils.java b/src/main/java/rocks/zipcode/quiz4/arrays/ArrayUtils.java
index 6deaf61..3087d9d 100644
--- a/src/main/java/rocks/zipcode/quiz4/arrays/ArrayUtils.java
+++ b/src/main/java/rocks/zipcode/quiz4/arrays/ArrayUtils.java
@@ -1,22 +1,54 @@
 package rocks.zipcode.quiz4.arrays;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
 /**
  * @author leon on 01/01/2019.
  */
 public class ArrayUtils {
     public static String getMiddleElement(String[] values) {
-        return null;
+        int middleIndex = (int) (values.length / 2);
+        String middle = values[middleIndex];
+
+        return middle;
+
     }
 
     public static String[] removeMiddleElement(String[] values) {
-        return null;
+        String middle = ArrayUtils.getMiddleElement(values);
+        List<String> al = new ArrayList<String>(Arrays.asList(values));
+
+        List<String> newList = al.stream().filter(x -> !x.equals(middle)).collect(Collectors.toList());
+        String[] result = new String[newList.size()];
+        newList.toArray(result);
+        return result;
+
     }
 
     public static String getLastElement(String[] values) {
-        return null;
+        String result = values[values.length - 1];
+
+        return result;
     }
 
     public static String[] removeLastElement(String[] values) {
-        return null;
+       // String last = getLastElement(values);
+
+
+        ArrayList<String> al = new ArrayList<>();
+        for(int i=0 ;i < values.length; i++){
+            al.add(values[i]);
+        }
+        al.remove(al.size()-1);
+        String[] result = new String[al.size()];
+        al.toArray(result);
+        return result;
+//        List<String> newList = al.stream().filter(x -> !x.equals(last)).collect(Collectors.toList());
+//        String[] result = new String[newList.size()];
+//        newList.toArray(result);
+//        return result;
     }
 }
\ No newline at end of file
diff --git a/src/main/java/rocks/zipcode/quiz4/collections/WordCounter.java b/src/main/java/rocks/zipcode/quiz4/collections/WordCounter.java
index 2bf5ec2..fc7d579 100644
--- a/src/main/java/rocks/zipcode/quiz4/collections/WordCounter.java
+++ b/src/main/java/rocks/zipcode/quiz4/collections/WordCounter.java
@@ -1,12 +1,24 @@
 package rocks.zipcode.quiz4.collections;
 
+import java.util.HashMap;
 import java.util.Map;
 
 public class WordCounter {
+    String[]strings;
     public WordCounter(String... strings) {
+        this.strings = strings;
     }
 
     public Map<String, Integer> getWordCountMap() {
-        return null;
+        Map<String,Integer>map = new HashMap<>();
+        for (int i = 0; i < strings.length ; i++) {
+            if(!map.containsKey(strings[i])){
+                map.put(strings[i],1);
+            }
+            else{
+                map.put(strings[i],map.get(strings[i])+1);
+            }
+        }
+        return map;
     }
 }
diff --git a/src/main/java/rocks/zipcode/quiz4/collections/culonary/Curry.java b/src/main/java/rocks/zipcode/quiz4/collections/culonary/Curry.java
index 199cefc..150128c 100644
--- a/src/main/java/rocks/zipcode/quiz4/collections/culonary/Curry.java
+++ b/src/main/java/rocks/zipcode/quiz4/collections/culonary/Curry.java
@@ -1,4 +1,16 @@
 package rocks.zipcode.quiz4.collections.culonary;
 
-public class Curry {
+public class Curry implements Spice{
+    private static Curry INSTANCE = new Curry();
+    private String name;
+
+    static Curry getInstance(){
+
+        return INSTANCE;
+    }
+
+    public String getName (){
+        return name;
+    }
+
 }
diff --git a/src/main/java/rocks/zipcode/quiz4/collections/culonary/Food.java b/src/main/java/rocks/zipcode/quiz4/collections/culonary/Food.java
index e06abbc..0de8bf4 100644
--- a/src/main/java/rocks/zipcode/quiz4/collections/culonary/Food.java
+++ b/src/main/java/rocks/zipcode/quiz4/collections/culonary/Food.java
@@ -1,20 +1,31 @@
 package rocks.zipcode.quiz4.collections.culonary;
 
+import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
 /**
  * @author leon on 27/12/2018.
  */
-public class Food {
+public class Food implements Spice{
+    List<Spice>spiceList = new ArrayList<>();
+
     public List<Spice> getAllSpices() {
-        return null;
+        return this.spiceList;
     }
 
     public <SpiceType extends Class<? extends Spice>> Map<SpiceType, Integer> getSpiceCount() {
-        return null;
+        Map<Class<? extends Spice>, Integer> map = new HashMap<>();
+        for (Spice spice : spiceList)
+            if (!map.containsKey(spice)) {
+                map.put(spice.getClass(), spiceList.size());
+            } else {
+                return null;
+            }
+       return (Map<SpiceType, Integer>) map;
     }
-
     public void applySpice(Spice spice) {
+        spiceList.add(spice);
     }
 }
diff --git a/src/main/java/rocks/zipcode/quiz4/collections/culonary/Ginger.java b/src/main/java/rocks/zipcode/quiz4/collections/culonary/Ginger.java
index 3c4e177..f276656 100644
--- a/src/main/java/rocks/zipcode/quiz4/collections/culonary/Ginger.java
+++ b/src/main/java/rocks/zipcode/quiz4/collections/culonary/Ginger.java
@@ -3,5 +3,10 @@
 /**
  * @author leon on 27/12/2018.
  */
-public class Ginger {
+public class Ginger implements Spice{
+    private static Ginger INSTANCE = new Ginger();
+
+    static Ginger getInstance(){
+        return INSTANCE;
+    }
 }
diff --git a/src/main/java/rocks/zipcode/quiz4/collections/culonary/Pepper.java b/src/main/java/rocks/zipcode/quiz4/collections/culonary/Pepper.java
index 4b771a8..c947f02 100644
--- a/src/main/java/rocks/zipcode/quiz4/collections/culonary/Pepper.java
+++ b/src/main/java/rocks/zipcode/quiz4/collections/culonary/Pepper.java
@@ -3,5 +3,10 @@
 /**
  * @author leon on 27/12/2018.
  */
-public class Pepper {
+public class Pepper implements Spice{
+    private static Pepper INSTANCE = new Pepper();
+
+    static Pepper getInstance(){
+        return INSTANCE;
+    }
 }
diff --git a/src/main/java/rocks/zipcode/quiz4/fundamentals/Calculator.java b/src/main/java/rocks/zipcode/quiz4/fundamentals/Calculator.java
index 02f2618..2eb9638 100644
--- a/src/main/java/rocks/zipcode/quiz4/fundamentals/Calculator.java
+++ b/src/main/java/rocks/zipcode/quiz4/fundamentals/Calculator.java
@@ -1,35 +1,58 @@
 package rocks.zipcode.quiz4.fundamentals;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
 /**
  * @author leon on 21/12/2018.
  */
 public class Calculator {
     public static Double squareRoot(Double value) {
-        return null;
+        return (Double) Math.sqrt(value);
     }
 
     public static Double square(Double value) {
-        return null;
+        return value * value;
+
     }
 
     public static Double[] squareRoots(Double... value) {
-        return null;
+
+        List<Double> al =new ArrayList(Arrays.asList(value));
+        List<Double> newList = new ArrayList<>();
+        for(Double x : al){
+            newList.add(Math.sqrt(x));
+        }
+        Double[] result = new Double[newList.size()];
+        newList.toArray(result);
+        return result;
+
     }
 
     public static Double[] squares(Double... values) {
-        return null;
+        List<Double> al =new ArrayList(Arrays.asList(values));
+        List<Double> newList = new ArrayList<>();
+        for(Double x : al){
+            newList.add(x*x);
+        }
+        Double[] result = new Double[newList.size()];
+        newList.toArray(result);
+        return result;
+
     }
 
     public static Double add(Double value1, Double value2) {
-        return null;
+
+        return value1 + value2;
     }
 
     public static Double subtract(Double value1, Double value2) {
-        return null;
+        return value1 - value2;
     }
 
 
     public static Double divide(Double divisor, Double dividend) {
-        return null;
+        return divisor/dividend;
     }
 }
diff --git a/src/main/java/rocks/zipcode/quiz4/fundamentals/StringUtils.java b/src/main/java/rocks/zipcode/quiz4/fundamentals/StringUtils.java
index 5ec61be..e150f44 100644
--- a/src/main/java/rocks/zipcode/quiz4/fundamentals/StringUtils.java
+++ b/src/main/java/rocks/zipcode/quiz4/fundamentals/StringUtils.java
@@ -1,34 +1,104 @@
 package rocks.zipcode.quiz4.fundamentals;
 
+import java.util.Arrays;
+
 /**
  * @author leon on 21/12/2018.
  */
 public class StringUtils {
     public static Character getMiddleCharacter(String string) {
-        return null;
+
+        char[] chars = string.toCharArray();
+        int middleIndex = chars.length / 2;
+        Character m = chars[middleIndex];
+        return m;
     }
 
     public static String capitalizeMiddleCharacter(String str) {
-        return null;
+        int middleIndex = str.length() / 2;
+        String result = "";
+        for (int i = 0; i < str.length(); i++) {
+            if (i != middleIndex) {
+                result = result + str.charAt(i);
+            }
+            if (i == middleIndex) {
+                result = result + Character.toUpperCase(str.charAt(i));
+            }
+
+
+        }
+        return result;
+
     }
 
     public static String lowerCaseMiddleCharacter(String str) {
-        return null;
+        int middleIndex = str.length() / 2;
+        String result = "";
+        for (int i = 0; i < str.length(); i++) {
+            if (i != middleIndex) {
+                result = result + str.charAt(i);
+            }
+            if (i == middleIndex) {
+                result = result + Character.toLowerCase(str.charAt(i));
+            }
+
+
+        }
+
+        return result;
+
     }
 
     public static Boolean isIsogram(String str) {
-        return null;
+        int len = str.length();
+
+        char arr[] = str.toCharArray();
+
+        Arrays.sort(arr);
+        for (int i = 0; i < len - 1; i++) {
+            if (arr[i] == arr[i + 1])
+                return false;
+        }
+        return true;
+
+
     }
 
     public static Boolean hasDuplicateConsecutiveCharacters(String str) {
-        return null;
+        int len = str.length();
+
+        char arr[] = str.toCharArray();
+        for (int i = 0; i < len - 1; i++) {
+            if (arr[i] == arr[i + 1])
+                return true;
+        }
+        return false;
+
     }
 
     public static String removeConsecutiveDuplicateCharacters(String str) {
-        return null;
+        StringBuilder sb = new StringBuilder();
+        for(int i = 0; i< str.length()-1; i++){
+            if(str.charAt(i) == str.charAt(i+1)){
+                i++;
+            }
+            else {
+                sb.append(str.charAt(i));
+            }
+        }
+        sb.append(str.charAt(str.length()-1));
+        return sb.toString();
+
     }
 
     public static String invertCasing(String str) {
-        return null;
+        String result = "";
+        for (int i = 0; i < str.length(); i++) {
+            if (str.charAt(i) == Character.toUpperCase(str.charAt(i))) {
+                result = result + Character.toLowerCase(str.charAt(i));
+            } else
+                result = result + Character.toUpperCase(str.charAt(i));
+        }
+        return result;
     }
 }
\ No newline at end of file
diff --git a/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Account.java b/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Account.java
index 40eb4a8..39e89a2 100644
--- a/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Account.java
+++ b/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Account.java
@@ -3,11 +3,16 @@
 /**
  * @author leon on 30/12/2018.
  */
-public class Account extends BankAccount {
+public class Account  {
+    private Long id;
+
+
+
     public Long getId() {
-        return null;
+        return this.id;
     }
 
     public void setId(Long id) {
+        this.id = id;
     }
 }
diff --git a/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Bank.java b/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Bank.java
index 0dd4183..b1bb288 100644
--- a/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Bank.java
+++ b/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Bank.java
@@ -1,17 +1,45 @@
 package rocks.zipcode.quiz4.objectorientation.account;
 
+import java.util.ArrayList;
+import java.util.List;
+
 /**
  * @author leon on 27/12/2018.
  */
 public class Bank {
+    List<BankAccount> bankAccountList;
+public Bank(){
+    bankAccountList = new ArrayList<>();
+}
+
+    public List<BankAccount> getBankAccountList() {
+        return bankAccountList;
+    }
+
+    public void setBankAccountList(List<BankAccount> bankAccountList) {
+        this.bankAccountList = bankAccountList;
+    }
+
     public BankAccount removeBankAccountByIndex(Integer indexNumber) {
-        return null;
+      bankAccountList.remove(bankAccountList.get(indexNumber));
+
+
+
+    return null;
     }
 
     public void addBankAccount(BankAccount bankAccount) {
-    }
 
+            bankAccountList.add(bankAccount);
+
+
+    }
     public Boolean containsBankAccount(BankAccount bankAccount) {
-        throw new UnsupportedOperationException("Method not yet implemented");
+        if (bankAccountList.contains(bankAccount)) {
+            return true;}
+            else
+
+            return false;
+        }
     }
-}
+
diff --git a/src/main/java/rocks/zipcode/quiz4/objectorientation/account/BankAccount.java b/src/main/java/rocks/zipcode/quiz4/objectorientation/account/BankAccount.java
index 70ccb74..50a68ec 100644
--- a/src/main/java/rocks/zipcode/quiz4/objectorientation/account/BankAccount.java
+++ b/src/main/java/rocks/zipcode/quiz4/objectorientation/account/BankAccount.java
@@ -3,7 +3,44 @@
 /**
  * @author leon on 27/12/2018.
  */
-public class BankAccount {
+public class BankAccount extends Account implements Transactable {
+    private Double balance;
+
+
+    public BankAccount()
+    {
+       balance = 0.0;
+    }
+    public BankAccount (Double balance){
+        this.balance = balance;
+    }
+
     public void setBalance(Double val) {
+
+        this.balance = val;
+    }
+
+    @Override
+    public void deposit(Double amountToIncreaseBy) {
+        if (amountToIncreaseBy >= 0) {
+            balance = balance + amountToIncreaseBy;
+        } else
+            throw new IllegalArgumentException();
     }
+
+    @Override
+    public void withdrawal(Double amountToDecreaseBy) {
+        if (amountToDecreaseBy <= balance && amountToDecreaseBy > 0) {
+            balance = balance - amountToDecreaseBy;
+        } else
+            throw new IllegalArgumentException();
+    }
+
+    @Override
+    public Double getBalance() {
+        return this.balance;
+    }
+
+
+
 }
diff --git a/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Employee.java b/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Employee.java
index 8407f1a..024416b 100644
--- a/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Employee.java
+++ b/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Employee.java
@@ -3,18 +3,75 @@
 /**
  * @author leon on 30/12/2018.
  */
-public class Employee {
-    public Employee() {
-    }
+public class Employee implements Worker, Transactable {
+    private BankAccount bankAccount;
+    private double hourlyWage;
+    private double hoursWorked ;
+    private double balace;
 
     public Employee(BankAccount bankAccount) {
-    }
+       this.bankAccount = bankAccount;
+       this.hourlyWage =35;
+     }
+    public Employee(){
+        bankAccount = new BankAccount();
+        this.hourlyWage = 35.0;
+        this.hoursWorked = 0.0;
 
+    }
     public BankAccount getBankAccount() {
-        return null;
+        return this.bankAccount;
     }
 
     public void setBankAccount(BankAccount bankAccount) {
+    this.bankAccount = bankAccount;
+    }
+
+    @Override
+    public void deposit(Double amountToIncreaseBy) {
+       this.bankAccount.deposit(amountToIncreaseBy);
+    }
+
+    @Override
+    public void withdrawal(Double amountToDecreaseBy) {
+    this.bankAccount.withdrawal(amountToDecreaseBy);
+    }
+
+    @Override
+    public Double getBalance() {
+        return this.bankAccount.getBalance();
+    }
+
+    @Override
+    public void setBalance(Double balance) {
+        this.balace = balance;
+    }
+
+    @Override
+    public void increaseHoursWorked(Double numberOfHours) {
+     hoursWorked += numberOfHours;
+    }
+
+    @Override
+    public Double getHoursWorked() {
+        return this.hoursWorked;
+    }
+
+    @Override
+    public Double getHourlyWage() {
+        return this.hourlyWage;
+    }
+
+    @Override
+    public Double getMoneyEarned() {
+        return  hourlyWage * hoursWorked;
+    }
+
+    public void setHourlyWage(double hourlyWage) {
+        this.hourlyWage = hourlyWage;
+    }
 
+    public void setHoursWorked(double hoursWorked) {
+        this.hoursWorked = hoursWorked;
     }
 }
diff --git a/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Transactable.java b/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Transactable.java
index 98a3dde..572f72a 100644
--- a/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Transactable.java
+++ b/src/main/java/rocks/zipcode/quiz4/objectorientation/account/Transactable.java
@@ -7,4 +7,5 @@ public interface Transactable {
     void deposit(Double amountToIncreaseBy);
     void withdrawal(Double amountToDecreaseBy);
     Double getBalance();
+    void setBalance(Double balance);
 }