Work Sampling: (2) a) A work sampling study is to be conducted with \(95\%\) confidence level \((Z=1.96)\) and \(5\%\) absolute accuracy. An initial estimate of a working activity is \(60\%\). How many observations should be made? (b) A work sampling study was conducted during an 80-hour period on 3 operators. During the study, tallies were made of when the operators were actually working on the three products \(\mathrm{A},\mathrm{B}\), and C . Of 300 observations, 100 were recorded as working on \(\mathrm{A},70\) on \(\mathrm{B},80\) on C, and the rest on other activities. During the time of the study the operators produced 200 of A,100 of B , and 30 of C. The observed ratings on the three products were 120,100, and 105 respectively. If the PFD allowances are \(20\%\) of standard time for all products, determine the standard times for the three products. (c) Determine the performance of the three operators in (b).