# probablity

1. ### Normalized Z-Table Questiong Is this right having problem with final answer

The amount of time it takes to produce a part is normally distributed with a mean equal to 10 second and standard deviation equal to 2 seconds. Fine the probability that the time it will take to produce any given part will be between 11 and 13.6 seconds. z = 11-10/2 = 1/2 = 0.5 z score =...
2. ### Choosing appropriate statistics (please)

Hi, I have an issue (mostly being clueless and trying to achieve more than I can), I am writing a page in Ruby on Rails for which I need to calculate the probability of two events being correlated (basically the likelihood of a trigger being the cause of a symptom, or since correlation doesn't...
3. ### Probability calculation problem for a ranked set sample

Let us consider a case where a ranked set sampling scheme from $n^2$ subjects has been adopted. There are a total of $n$ RSS blocks. So each RSS block contains $n$ subjects. We will follow up them. Some of these subjects will fulfill a certain criterion and get a treatment and some will not be...
4. ### No clue when to use nCr or multiply the probabilites..

I'm completely baffled as to when to use nCr or multiply the probabilites.. Here's an example.. Jane buys 5 jam donuts, 4 cream donuts and 3 plain donuts. Calculate the probabilities of the following events. A)All 3 donuts eaten contain jam.. B) the 3 donuts are of different kind. Why wouldn't...