Concept:
Time Study:
Observed Time (OT): It is the time observed by an observer
Normal Time (NT): It is the time required to complete a job by a normal average worker under normal working conditions.
NT = OT × Rating Factor (RF)
Allowances: It is the extra time provided to the worker above the NT to work continuously for a long duration. The allowance is always given with respect to normal time.
Allowance = % of Normal Time
Standard Time: It is required to complete a job by taking all the uncertainty related to the production system into account.
ST = NT + Allowances
Calculation:
Given:
Time taken for five observations are recorded as 40, 35, 45, 37 and 43 seconds
Stadard Time (ST) = 45 seconds, Allowance = 9 seconds
Average Observation Time:
OT \( = \frac{{40\; + \;35\; + \;45\; + \;37\;+\;43}}{5} = 40\; \rm seconds\)
ST = NT + Allowance
45 = NT + 9
∴ NT = 36
NT = OT × RF
36 = 40 × RF
RF = 0.9 = 90 %