Pet Products Company uses an automated process to manufacture its pet replica products. For June, the company had the following activities: 

Beginning work-in-process inventory	4500 items, 1/4 complete
Units placed in production	15 000 units
Units completed	17 500 units
Ending work-in-process inventory	2000 items, 3/4 complete
Cost of beginning work in process	$5250
Direct material costs, current	$16 500
Conversion costs, current	$23 945

Direct materials are placed into production at the beginning of the process and conversion costs are incurred evenly throughout the process. 

Required: 

a) Prepare a production cost worksheet using the FIFO method.
 b) What is the difference between a weighted-average method of process costing and a first- in, first-out method of process costing?