i) Estimate the standard time per piece of a job whose normal time is 2 minutes.

ii) Find number of pieces to be produced per day.

iii) If the workmen engaged on the above job produced 180 pieces in the shift, what 1s their efficiency?

Total minutes in a shift $=8 \times 60=480$

Normal Time $=2$ minutes

Allowances $=480-400=80$ minutes

Percentage Allowance $=\frac{\text {Rest timing } \times 100}{\text { Available work timing}}$ $=\frac{80 \times 100}{400}=20 \%$

$\begin{aligned} \text {a. Standard time } &=\text { Normal time }(1+\text { allowance percentage })\\ &=2(1+0.20)=2.4 \text { minutes } \end{aligned}$

$\begin{aligned} \text {b. No. of pieces to be produced per day} &=\frac{\text { Total time available for production }}{\text {standard time per piece}} \\ &=\frac{480}{2.4}=200 \ \text{pieces/day} \end{aligned}$

$\begin{aligned} \text {c. Operator's efficiency} &=\frac{\text { Produced Quantity } X 100}{\text { Standard production quantity}} \\ &= \frac{180 \times 100}{200}=90 \% \end{aligned}$