diff --git a/src/es05_bank.rs b/src/es05_bank.rs
new file mode 100644
index 0000000..3de3343
--- /dev/null
+++ b/src/es05_bank.rs
@@ -0,0 +1,144 @@
+#![allow(dead_code)]
+
+use std::{fmt::Debug, rc::Rc};
+
+use self::states::AccountState;
+
+/**
+ * Dovete implementare un ContoBancario che ha come informazioni
+ * - nome del cliente (una stringa)
+ * - ammontare del saldo
+ * - limite inferiore
+ * - limite superiore
+ * - interesse
+ *
+ * Le operazioni che si vogliono fare sono:
+ * - deposita che aggiunge al saldo la quantità depositata
+ * - preleva che rimuove dal saldo la quantità prelevata
+ * - paga gli interessi che aggiunge al saldo il saldo per l'interesse
+ *
+ * Queste operazioni hanno comportamenti diversi a seconda dello stato del conto, che può essere
+ * - Rosso (se il saldo e' minore del limite inferiore)
+ * - Argento (se il saldo e' minore del limite superiore e maggiore di quello inferiore)
+ * - Oro (se il saldo e' maggiore del limite superiore)
+ *
+ * In particolare:
+ * - prelevare da un conto Rosso non fa niente e cosi' pure paga interessi
+ * - paga interessi in un conto Argento non fa niente
+ *
+ *
+ * L'implementazione deve essere fatta usando il Pattern State.
+ * Dovete implementare un crate lib (quindi senza main)
+ * Mettere i test nella directory tests
+ */
+#[derive(Debug)]
+pub struct BankAccount {
+    name: String,
+    balance: f32,
+    limit_hi: f32,
+    limit_lo: f32,
+    interest: f32,
+    state: Rc<dyn AccountState>,
+}
+
+impl BankAccount {
+    pub fn new(name: String, limit_lo: f32, limit_hi: f32, interest: f32) -> Self {
+        assert!(
+            limit_hi >= 0.0 || limit_lo >= 0.0,
+            "The limits must have a positive value!"
+        );
+        assert!(
+            interest >= 0.0 && interest <= 1.0,
+            "The interest must have a value between 0 and 1!"
+        );
+
+        Self {
+            name,
+            balance: 0.0,
+            limit_hi,
+            limit_lo,
+            interest,
+            state: Rc::new(states::Red),
+        }
+    }
+
+    pub fn balance(&self) -> f32 {
+        self.balance
+    }
+
+    pub fn state(&self) -> String {
+        format!("{:?}", self.state.as_ref())
+    }
+
+    pub fn deposit(&mut self, amount: f32) {
+        if amount > 0.0 {
+            self.balance += amount;
+            self.set_state();
+        }
+    }
+
+    pub fn withdraw(&mut self, amount: f32) {
+        if amount > 0.0 {
+            let state = Rc::clone(&mut self.state);
+            state.withdraw(self, amount);
+            self.set_state();
+        }
+    }
+
+    pub fn pay_interest(&mut self) {
+        let state = Rc::clone(&mut self.state);
+        state.pay_interest(self);
+        self.set_state();
+    }
+
+    fn set_state(&mut self) {
+        self.state = if self.balance < self.limit_lo {
+            Rc::new(states::Red)
+        } else if self.balance > self.limit_hi {
+            Rc::new(states::Gold)
+        } else {
+            Rc::new(states::Silver)
+        };
+    }
+}
+
+/*********************************************
+ * Trait for States and implementations of it
+ */
+pub mod states {
+    use std::fmt::Debug;
+
+    use super::BankAccount;
+
+    pub trait AccountState: Debug {
+        fn withdraw(&self, account: &mut BankAccount, amount: f32);
+        fn pay_interest(&self, account: &mut BankAccount);
+    }
+
+    #[derive(Debug)]
+    pub struct Red;
+    impl AccountState for Red {
+        fn withdraw(&self, _account: &mut BankAccount, _amount: f32) {}
+        fn pay_interest(&self, _account: &mut BankAccount) {}
+    }
+
+    #[derive(Debug)]
+    pub struct Silver;
+    impl AccountState for Silver {
+        fn withdraw(&self, account: &mut BankAccount, amount: f32) {
+            account.balance -= amount;
+        }
+        fn pay_interest(&self, _account: &mut BankAccount) {}
+    }
+
+    #[derive(Debug)]
+    pub struct Gold;
+    impl AccountState for Gold {
+        fn withdraw(&self, account: &mut BankAccount, amount: f32) {
+            account.balance -= amount;
+        }
+        fn pay_interest(&self, account: &mut BankAccount) {
+            account.balance -= account.balance * account.interest;
+        }
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 0278b59..b33b911 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2,3 +2,5 @@ pub mod es01_anagram;
 pub mod es02_rational;
 pub mod es03_game;
 pub mod es04_rational_traits;
+pub mod es05_bank;
+
diff --git a/tests/es05_bank.rs b/tests/es05_bank.rs
new file mode 100644
index 0000000..cca0c83
--- /dev/null
+++ b/tests/es05_bank.rs
@@ -0,0 +1,37 @@
+use esercizi::es05_bank::BankAccount;
+
+#[test]
+fn test_bank() {
+    let name = "Nome".to_string();
+    let mut account = BankAccount::new(name.clone(), 1000.0, 10000.0, 0.02);
+    assert_eq!(account.balance(), 0.0);
+    assert_eq!(account.state(), "Red");
+
+    account.deposit(1001.0);
+    assert_eq!(account.balance(), 1001.0);
+    assert_eq!(account.state(), "Silver");
+
+    account.pay_interest();
+    assert_eq!(account.balance(), 1001.0);
+    assert_eq!(account.state(), "Silver");
+
+    account.withdraw(100.0);
+    assert_eq!(account.balance(), 901.0);
+    assert_eq!(account.state(), "Red");
+
+    account.withdraw(1.0);
+    assert_eq!(account.balance(), 901.0);
+    assert_eq!(account.state(), "Red");
+
+    account.deposit(100000.0);
+    assert_eq!(account.balance(), 100901.0);
+    assert_eq!(account.state(), "Gold");
+
+    account.pay_interest();
+    assert_eq!(account.balance(), 98882.98);
+    assert_eq!(account.state(), "Gold");
+
+    account.withdraw(90882.98);
+    assert_eq!(account.balance(), 8000.0);
+    assert_eq!(account.state(), "Silver");
+}