diff --git a/a1.py b/a1.py
index bcae5df..5199a35 100644
--- a/a1.py
+++ b/a1.py
@@ -65,6 +65,24 @@ def determine_water_released(gen_power: float, elevation: float, pumping_time: f
     return water_mass
 
 # Task 3
+def determine_cost_to_pump(gen_power: float, pumping_time: float, off_peak_tariff: float) -> float:
+    """
+    Calculates the cost of using the pump during off peak period
+
+    Parameters:
+        gen_power (float): the amount of power generated by the pump [kW]
+        pumping_time (float): the amount of time the pump is running for [hrs]
+        off_peak_tariff (float): the off-peak tarriff cost for electricity [$/kWh]
+
+    Returns:
+        (float): the cost of running the pump ($)
+    """
+
+    cost = gen_power * pumping_time * off_peak_tariff
+
+    return cost
+
+
 
 
 # See if I get what the task sheet wants
@@ -72,7 +90,8 @@ def sheet_tasks():
     import numpy as np
     TASKS = (
         (determine_power_used, (5e6, 250, 8, 85), 500.9191176470588),
-        (determine_water_released, (300, 250, 8, 85), 2994495.4128440367)
+        (determine_water_released, (300, 250, 8, 85), 2994495.4128440367),
+        (determine_cost_to_pump, (300, 8, 0.02), 48), 
     )
 
     for i, (task, args, expected) in enumerate(TASKS):