1. Estimate the proportion of modules in the portfolio that are Y2K
   compliant

           Since the sample proportion is 60% then assuming the 
           sample is representative of the population (i.e. the 
           portfolio) then 60% is a good estimate of the portfolio
           proportion.
         
2. Determine the "error" in your estimate for 1. above.

           The error in the estimate is given by S(p). Since n=120
           then S(p) is:
                      S(p)=sqrt(0.6*0.4)/120)=0.0447
           Hence the "error" is 0.0447 or expressed as a percentage
           is 4.47%.

3. What is the "margin of error". Interpret your answer.
 
           Margin of error is approximately 2*S(p)=2*4.47=8.94%.
           Since p +/- "margin of error" is approximately a 95%
           CI then we may say that we are approximately 95% 
           confident that the portfolio proportion is between
           51% and 69% (rounded).