1. The WAB Bank decided to open up two new drive-through teller windows outside its main office building in Sariaya, Quezon. The bank is not sure that it needs both windows open all day so it has decided to conduct work sampling study to determine the proportion of time the two tellers are idle between the hours of 10:00AM to 11:30 AM and 1:00 PM to 3:00 PM. The work sampling study was conducted at random over a five-day period and the following observations were recorded: (table on the file)
2. Bank management wants the study to be +/- 5% accurate with a 95% confidence level. How many additional sample observations should be taken? (refer to table)