why in process account, by finished goods amount is $72310,$ ?not $67230?$

A company produces a single product from one process and the following data were related to a period: Opening Work in Progress - 2,000 units Materials Labour Overheads Costs incurred in the period were: Materials Labour Overheads Units added in the period: 10,000 units Units completed in the period: 9,000 units Closing Work in Progress: 3,000 units Cost Degree of ($) completion 3,900 50% 2,240 40% 1.080 30% 7.220 39,200 29,100 19,200