Sheffield Company began operations on January 1, 2015, and uses the average-cost method of pricing inventory. Management is contemplating a change in inventory methods for 2018. The following information is available for the years 20152017.

Net Income Computed Using

	Average-Cost Method	FIFO Method	LIFO Method
2015	$16,110	$18,880	$12,030
2016	$17,960	$20,820	$13,910
2017	$20,000	$24,850	$17,140

(a) Prepare the journal entry necessary to record a change from the average cost method to the FIFO method in 2018.

(b) Determine net income to be reported for 2015, 2016, and 2017, after giving effect to the change in accounting principle.

(c) Assume Sheffield Company used the LIFO method instead of the average cost method during the years 20152017. In 2018, Sheffield changed to the FIFO method. Prepare the journal entry necessary to record the change in principle.