Note that the sample size is only 8 and you don’t know whether the population from which the sample is drawn is normally distributed or not. In this situation use the t distribution. Put the numbers into Excel and then find the margin of error using the t distribution.....go to data analysis> descriptive stats and it is the number at the bottom of the table.
My results are:
Standard Error 1.224745
Standard Deviation 3.464102
Sample Variance 12
Confidence Level(95.0%) 2.896061
So for 13 (a) xbar is 10; for (b) 3.464, and (c) is 2.896. The last question is the Confidence Interval. That’s easy: 10 – 2.896 and 10 + 2.896....note you MUST actually finish off this little calculation.
Difference between cluster sampling and stratified: think of cluster being used for spatial problems, such as the example about trees with beetles in BC. Stratified is used when we can easily divide the population into homogeneous groups, for example golf-club membership