Biology Forums - Study Force

Senior management of a consulting services firm is concerned about a growing decline in the
firm’s weekly number of billable hours. The firm expects each professional employee to spend
at least 40 hours per week on work. In an effort to understand this problem better, management
would like to estimate the standard deviation of the number of hours their employees spend on
work-related activities in a typical week. Rather than reviewing the records of all the firm’s
full-time employees, the management randomly selected a sample of size 51 from the available
frame. The sample mean and sample standard deviations were 48.5 and 7.5 hours,
respectively.

Construct a 90% confidence interval for the standard deviation of the number of hours this
firm’s employees spend on work-related activities in a typical week.

Place your LOWER limit, in hours, rounded to 1 decimal place, in the first blank. For example,
6.7 would be a legitimate entry.

Place your UPPER limit, in hours, rounded to 1 decimal place, in the second blank. For
example, 12.3 would be a legitimate entry.

Try the following...