Question 1086348: Specify whether you will use a normal distribution, t-distribution or neither for the below examples:
200 people were surveyed and it was determined that they watched an average of 65 minutes of TV per day and are normally distributed. The mean sample standard deviation is 21.3 minutes.
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! It's not clear what one wishes to know, so strictly speaking,none of the above. If one wishes a confidence interval of the population, one would classically use a z-test, because the sample is normally distributed and the size is over the "magic" 30, which I don't agree with (but many do). When I construct a confidence interval, for example, I will use a t-test if I am estimating the standard deviation from the sample. With large sample sizes, the t will approach the z, and it makes no difference, but it forces one to realize what is being done rather than just using z because the sample size is large. The distribution is a t-distribution.
The answer is likely normal z distribution (z-needs to be stated) because of sample size, but the actual one is a t which at these degrees of freedom (199) is almost the same.
|
|
|
