diff --git a/Week01/info_ertugrul_kose.py b/Week01/info_ertugrul_kose.py
new file mode 100644
index 00000000..301759a2
--- /dev/null
+++ b/Week01/info_ertugrul_kose.py
@@ -0,0 +1,2 @@
+student_id = "210316038"
+full_name = "Ertuğrul Köse"
diff --git a/Week02/weighted_ertugrul_kose.py b/Week02/weighted_ertugrul_kose.py
new file mode 100644
index 00000000..47d253f5
--- /dev/null
+++ b/Week02/weighted_ertugrul_kose.py
@@ -0,0 +1,7 @@
+import random
+
+def weighted_srs(dataset, k, w, with_replacement=False):
+    if with_replacement or w:
+        return random.choices(dataset, weights=w, k=k)
+    else:
+        return random.sample(dataset, k)
diff --git a/Week03/shifted_ertugrul_kose.py b/Week03/shifted_ertugrul_kose.py
new file mode 100644
index 00000000..f66cdf2e
--- /dev/null
+++ b/Week03/shifted_ertugrul_kose.py
@@ -0,0 +1,11 @@
+def shifted(values):
+    n = len(values)
+    sorted_vals = sorted(values)
+    avg = sum(values) / n
+
+    if n % 2 == 0:
+        med = (sorted_vals[n // 2] + sorted_vals[n // 2 - 1]) / 2
+    else:
+        med = sorted_vals[n // 2]
+
+    return abs(avg - med) / abs(avg) * 100