statistics
posted by Tracer .
A sample of n = 20 scores has a mean of M = 6. If one new person with a score of X = 27 is added to the sample, what will be the value for the new mean?

Mean = Σx/n
6 = Σx/20
Σx = 120
new Σx = 120 + 27 and new n = 21
Use the above equation to calculate new mean. 
one sample has a mean of M= 4 and a second sample has a mean M=8. The two samples are combined into a single set of scores.
a. What is the mean for the combined set if both of the original samples have n= 7scores?
What is the mean for the combined set if the first sample has n= 3 and the second sample has n= 7?
What is the mean for the combined set if the first sample has n= 7 and the second sample has n= 3?