For a manual operation, observed time data are given below:
Recorded time : 15 minute
Rating of the worker : 80%
Personal allowance : 0.6 minute
Basic fatigue allowance : 0.8 minute
Contingency work allowance : 1.2 minute
Unavoidable delay allowance : 1.1 minute
What is the standard time for the operation?
(a) 16.4 minute (b) 17.5 minute
(c) 18.5 minute (d) None of the above