1. A CTI student is interested in comparing the programming skill of SE
   and CS graduate students. His colleagues argue that both groups, on
   average, have the same skill level but the student believes that SE 
   students can develop "working" software more quickly.
   
   The student decides to focus on students who have completed both the
   pre-requisite and core phases. He selects random samples from each
   group and asks them to participate in a non-trivial programming  
   assignment. He provides assignments to 40 CS and 35 SE students and
   records the time that each student takes to code and debug the
   program. He discovers that the mean time for CS students is 5.0
   hours with standard deviation 1.1 hour and for SE students the mean
   is 4.6 hours with standard deviation 1.08 hours.

   a) Conduct a test of hypotheses.
   b) Given your findings, is a point estimate appropriate? If so,
      provide a point estimate of the difference in average coding time as 
      well as a 90% CI.

2. An electronic retailer asks an indenpent usability expert to evaluate
   a browser based GUI proposed by a software consulting firm. The 
   retailer doubts the claim that the new interface will allow novice
   users to complete tasks more quickly. The expert selects two random
   samples of novice users and assigns the proposed GUI to one group
   and the existing GUI to the other group. Each group has 14 users.
   He discovers that the mean task completion time for the proposed GUI
   is 250 seconds with standard deviation 71 seconds and for the existing
   GUI the mean time is 315 seconds with standard deviation 86 seconds.

   a) Conduct a test of hypotheses.
   b) Given your findings, is a point estimate appropriate? If so,
      provide a point estimate of the difference in average coding time as 
      well as a 90% CI.
   c) Determine the minimum sample size required to estimate the
      difference in task completion time to an accuracy of 10 seconds
      with 99% confidence.