tutorny
Posts:
39
Registered:
1/28/06


Re: Help with probability&stat problem
Posted:
Jun 11, 2007 1:34 PM


> Do you really think there is a 97% chance that > there will be a 30% drop out rate? Suppose I asked > you the probability that 100 of the students would > drop out. How would you calculate that? Do you think > that is a higher probability than only 30 students > dropping out?
I am not entirely sure that I follow. 30 students out of 110 is 27%. So if a 20% rate is to be expected, isn't it feasible that a 27% rate is 96% likely?
If I made the mistake there, it would be in making p = 0.20. So, I think what you are saying is that p should be = 0.80. But doing the calculations that way results in a nonsensical answer..
If p =0.80 : mean = 88, s.d. = 4.1952 and for x = 29.5, z = 13.944 which doesn't make any sense.
So where did I go wrong? Or am I not understanding your comment correctly?

