The total costs on job cost sheets for jobs that are not yet completed equals the balance in the Work in Process Inventory account.

This is because the Work in Process Inventory account is a control account that reflects the total cost of all jobs that are currently in progress and have not yet been completed. The job cost sheets contain detailed information about the costs incurred on each individual job, which are used to update the Work in Process Inventory account. Once a job is completed, its total cost is transferred from Work in Process Inventory to Finished Goods Inventory or Cost of Goods Sold depending on whether the goods or services produced have been sold or not.