A work sampling study was conducted for 100 hours in the machine shop in order to estimate the standard time.The total number of observations recorded was 2500.

No working activity could be noticed for 400 observations. The ratio between manual and machine elements was 2:1. Average rating factor was estimated as 1.15 and the total number of articles produced during the study period was 6000. Rest and personal allowances are 12% of the normal time. Estimate standard time to perform the operation.

1 Answer


Overall time per piece $\left[T_{O}\right]$

$T_{o}=\frac{\text {Duration of study in minutes}}{\text {No.of pieces produced during study}}=\frac{100 \times 60}{2500}=2.4$ minutes

Effective time per piece $\left[T_{e}\right]$

$T_{e}= \text{Over all time per piece} \times \frac{\text { Productive observations}}{\text { Total observations}}=T_{o} \times \frac{N_{p}}{N}$

$=2.4 \times \frac{2500-400}{2500}=2.016$ minutes

Machine controlled time per piece $=T_{m}=2.016 \times \frac{1}{3}=0.672$ minute

Hand controlled time per piece $=T_{h}=2.016 \times \frac{2}{3}=1.344$ minutes

Normal time per piece $=T_{m}+T_{h} \times R =0.672+(1.344 \times 1.15)=2.2176$ minutes

Standard time per piece $=$ Normal time $+$ Allowances $=2.2176+(1+0.12)=3.3376$ minutes

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