3b) For a work sampling study, it has been observed that machine repair consumes 50 percent of maintenance worker's time. Management want the estimate to be within 5 percent of the true proportion at 95 percent confidence ( 2 =1.96). Determine the number of observations required to achieve that. (4 marks) 3c) A time study was conducted on a job that contains four elements. The observed times and performance ratings for six cycles are shown in the following Table. (7 marks) Element 1 2 3 4. Performance rating 90% 85 110 100 1 0.44 1.50 0.84 1.10 Observations (minutes/cycle) 2 3 4 5 0.50 0.43 0.45 0.48 1.54 1.47 1.51 1.49 0.89 0.77 0.83 0.85 1.14 1.08 1.20 1.16 6 0.46 1.52 0.80 1.26 i 11. Determine the average cycle time for each element. Find the normal time for each element. Assuming an allowance factor of 15 percent of the job time, compute the standard time for this job