Data from an 8-hour work sampling study are shown below. a) What % of the time is

Question:

Data from an 8-hour work sampling study are shown below.
a) What % of the time is the machine running?
b) What % of the time is the machine broken?
c) What is the limit of accuracy of this study?
d) What is 95% confidence interval of the machine running?
e) Your manager says that the range in part d) is unacceptably large. She would like to narrow the range down to ± 1 minute of running time. How many observations should you collect to achieve this?