The water level of a river in the city of Melbourne changed by − 414 feet over a 3-month period. Which of these describes the average monthly change in the water level of the river?
On an average, the water level decreased by 114 feet per month.
On an average, the water level decreased by 1512 feet per month.
On an average, the water level decreased by 1234 feet per month.
On an average, the water level decreased by 1112 feet per month.