diff --git a/medium/average_wait_time.py b/medium/average_wait_time.py
new file mode 100644
index 0000000..dc1a03b
--- /dev/null
+++ b/medium/average_wait_time.py
@@ -0,0 +1,15 @@
+# https://leetcode.com/problems/average-waiting-time/
+from typing import List
+
+class Solution:
+    def averageWaitingTime(self, customers: List[List[int]]) -> float:
+        available = customers[0][0]
+        waiting = 0;
+        for time in customers:
+            if time[0] < available:
+                waiting += available - time[0]
+            else:
+                available = time[0]
+            waiting += time[1]
+            available += time[1]
+        return waiting / len(customers)