1. The average observed time for a given job is 10 minutes. The performance rating is 80%, and allowances are set by contract at 8%. What is the standard time?
2. The data below represent time study observations for an assembly operation. Assume a 7% allowance factor. What is the normal time for element 2?

		Observations (times in minutes)
Element	Performance Rating	1	2	3	4	5
1	100%	1.5	1.6	1.4	1.5	1.5
2	90%	2.3	2.2	2.1	2.2	2.4
3	115%	1.7	1.9	1.9	1.4	1.6
4	100%	3.5	3.6	3.6	3.6	3.2

3. The accuracy of a labour standard is to be within 5%, and the confidence level is 95%. The standard deviation of the sample is 2 and the mean is 9.5. What sample size should be used?
4. A bank manager wants to determine the per cent of time the bank's tellers are working and idle. He decides to use work sampling, and his initial estimate is that the tellers are idle 22% of the time. Approximately how many observations should be taken to be 95% confident that the results will not be more than 5% away from the true result?