Statistics
posted by Amy .
Two problems:
1. Find D sub 3 of the following data set:
60, 40, 26, 33, 23, 53, 36, 23, 28, 12, 30, 47
2. Find P sub 26 of the following 25 scores:
38.5, 41.5, 52, 52.5, 61, 63, 63.5, 68, 69, 69, 78.5, 79, 80, 83, 87, 88.5, 88.5, 91, 91.5, 92, 92.5, 94, 94, 97, 97
I have a formula that says (Xmean)/standard deviation, but I'm not really sure if/how that helps here.
Help is greatly appreciated!

What do you mean by "D sub 3"
Does "P sub 26" mean the projected value of the 26th observation? If so, and if the scores are in sequential order, you could run a linear regression to get the projected value.
Xmean/SD is the inverse of the "coefficient of variation". I cant see why this is relevant here. 
It was Decile 3 and the 26th percentile. I worked it out with my teacher in class today.
I appreciate the effort though :)