Question

A time study is carried out for a spot welding operation which is being performed by an operator. The time taken (in seconds) for five observations are recorded as 40, 35, 45, 37 and 43, respectively. If the standard time and the allowance for this operation are 45 seconds and 9 seconds, respectively, then the performance rating (in percentage) of the operator is ________. [in integer]

Answer 1

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 %