statistics
posted by Joan .
A set of seven scores has a mean of 10. If one of the scores is changed from X=15 to X=1, what will be the new value for the new mean?
A sample of n=8 scores has a mean of M=12. One new score is added to the same and the new mean is found to be M=13. What is the vaule of the new score?
What steps do I follow to figure out these types of problems? I don't quite understand how the book is explaining it.

If a set of seven numbers has a mean of 10, then the sum of the ten numbers must be 70. If you raise one of thme from 1 to 15, than the total becomes 84. Divide that by 7 for the new mean value.
Use a similar approach for the second question. The total for the first 8 numbers is 8x12 = 96. When a ninth number is added, the total becomes 9x13 = 117. How much did the thirteenth number add to the total?
Respond to this Question
Similar Questions

statistics
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? 
algebra
tenequal scores have a mean of 30. if one score is doubled, and the other nine remain the same, what is the mean of the new set of scores? 
statistics
A population of N=8 scores has a mean of M =20. If one score is changed from X=14to X=30 , what would be the value for the new mean. 
statistics
A population of N=8 scores has a mean of µ = 20. If one score is changed from X=14 to X=50, what will be the value for the new mean? 
statistics
A population of N=8 scores has a mean of µ = 20. If one score is changed from X=14 to X=50, what will be the value for the new mean? 
Stats
a population of 8 scores has a mean of 11. If one of the scores in this population is changed from x=9 to x=25, what value would be obtained for the new population mean? 
Statistics
For a population with a mean of (mew) = 50 and a standard deviation of 10, how much error, on average, would you expect between the sample mean (M) and the poulation mean for: a) a sample of n=4 scores b) a sample of n=16 scores c) … 
probability and statistics
a population forms a normal distribution with a mean of u=80 and a standard deviation of o=15. for each of the following samples, compute the zscore for the sample mean and determine whether the sample mean is a typical, representative … 
Math
I need help with this these two problem PLEASE!!! For a population with a mean of μ 80 and a standard deviation of 12, find the zscore corresponding to each of the following samples. a. M 83 for a sample of n 4 scores … 
Stats
A sample of n=9 scores has a mean of M=20. One of the scores is changed and the new mean is found to be M=22. If the changed score was originally X=7, what is the new value?