ARCHIVE - Stats 10-5

We will look at the answers to some of the questions.

The r.m.s. is the root mean square and that tells you the size of the data values = sqrt(average(entries ** 2)).
What is the rms for -1, 1, 3?
standard deviation measures how far the numbers are away from their average. (review) Take histogram in figure 8, with average = 63.5, and SD = 2.5 What is the percent of people within 1 SD from the average? 66% What about 2 SD from the average? 95%
SD = sqrt(average (deviationFromMean **2))
examples:
1. compute average and SD for:
```
     (i)   1, 3, 4, 5, 7
     (ii)  6, 8, 9, 10, 12
     
```
  how do the averages and SD's compare?
2. compute average and SD for:
```
     (i)   1, 3, 4, 5, 7
     (ii)  3, 9, 12, 15, 21
     
```
  how do the averages and SD's compare?
3. compute average and SD for:
```
     (i)   5, -4, 3, -1, 7
     (ii)  -5, 4, -3, 1, -7
     
```
  how do the averages and SD's compare?
4. What is the r.m.s. size of the list: 17, 17, 17, 17, 17? SD?
If the average is 0, then rms is the SD
For a list of positive numbers, can the SD ever be larger than the average?