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.

Solution:

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