Statistics Questions

Question

These are all similar problems, I am just not understanding the process. When I try how the book explains it, it comes out different.

1. A sample of n=7 scores has a mean of M=9. If one new person with a score of X=1 is added to the sample, what is the value for the new mean?

2. A sample of n=15 scores has a mean of M=6. One person with a score of X=22 is added to the sample. What is the value for the new sample mean?

3. A population of N=15 scores has a mean of µ=8. One score in the population is changed from X=20 to X=5. What is the value for the new population mean?

4. A sample of n=7 scores has a mean of M=5. After one new score is added to the sample, the new mean is found to be M=6. What is the value for the new score?

5. One sample of n=12 scores has a mean of M=7 and a second sample of n=8 scores has a mean of M=12. If the two samples are combined, what is the mean for the combined sample?

Answer 1

1.  The average is 9, and there are 7 scores, so total of scores must be 63.  Along comes new score, 1, so total is 64 and now n = 8.  Mean(average) is now 8.  Note Greek letter mu (μ) another name for mean, which was called M here.

 

Same principle as used above in 1 can be applied to the remainder of these problems.