A staff assistant at Worthtington Corporation recently determined that the first five units completed in a new manufacturing process took $2,375$ hours to complete, or an average of $475$ hours per unit. The assistant also found that when the cumulative output produced doubles, the average labor time declines by $20\%.$ How many total hours would Worthington use if it produces a cumulative amount of $40$ units?

$608$

$760$

None of the answers is correct

$9,728$

$6,080$