Sample observations of a claims processor made over a 160 hour work month reveal that the worker produced a total of 384 completed claims forms. The performance rating was 80%. The worker was idle 20% of the time. The allowance factor is 8%. What is the standard time per unit? a. 0.42 min, b. 16.0 min c. 17.4 min d. 20.0 min. e 21.7 min