A total of 300 observations of Bob Ramos, an assembly-line worker, were made over a 40-hour workweek. The sample also showed that Bob was busy working (assembling the parts) during 250 observations.
a) Find the percentage of time Bob was working.
b) If you want a confidence level of 95%, and if {3% is an acceptable error, what size should the sample be?
c) Was the sample size adequate?