Probability Question: prob. of finishing project within....

[suicoted]

The fastest project completion time is 11.49 weeks. At this completion time, what would the probability of finishing the project within 29.43 weeks?

I don't quite understand what the question means, and what X and "mu" should be. I would like some help on setting up the bell curve, so I can find z scores. Thanks.

SD: 3.74 weeks

When I did it, I got -4.79 because I let X = 11.49 and mu = 29.43. I don't know how to handle a z score of -4.79. My table goes up to 3.09 for z-table
Please let me know if my method was right, thanks.

 

[rzornick]

This is kinda a strange question and it kinda assmes a lot but what i think you can do is use the equation for findind a z score using z=-3.09, 11.49 as X, and the standard deviation 3.74 weeks to find mu. You then can set up a normal distribution using that mu and standard deviation and find you z-score for 29.43.
I ended up with mu=23.0466 so using that, there ends up being about a 97.5% it will bein less time. However, using different z scores for the minumum value will give you different mu's which will also give different probabilities. Maybe i'm missing something but it seems to me that there should be some other pice of information such as a population size to actually arrive at a more meaningful answer.