Hello, I am really having trouble with this one:
Q. Data collected over a long period of time show that a particular genetic defect occurs in 1 of every 1000 children. The records of a medical clinic show x=60 children with the defect in a total of 50,000 examined. If the 50,000 were a random sample from the population of children represented by past records,What is the probability of observing a value of X eqaul to 60 or more?
Any help will be greatly appreciated,
Cheers, RaVS
The condition that I use when considering the normal approximation is . In practice this means that
Depending on the time of day and wind direction this can mean anything from to , or if we are discussing very low probability events to never (low probability events that occur in certain safety analyses for example).
Actually that is not what I usually do; I always first consider the normal approximation and only if the answer using that is not blindingly clear do I resort to exact calculation (or a better approximate method), that and the desire to impress simple minds. Reality does not really support high precision probability calculations, but we don't tell the punters this.
CB