Programing the hp33s

The standard deviation is a measure of how "tight" the samples are distributed around your mean.
In layman's terms, a small standard deviation indicates that most of your measurements are in the vicinity of the means; a large standard deviation corresponds to readings that are all over the place.
You could also say that the smaller the SD, the more your mean is representative of the data set.
For a better explanation, just look up Standard deviation on Wikipedia!

To convert an x value to a z-score, the formula is:
(x value - mean)/standard deviation

Example: We have a number of height measurements that have a mean of 65.25 and a standard deviation of 2.84. One value is 68.5. To convert it to a z-score: (68.5-65.25)/2.84 = 1.144

Hope this helps!

The standard deviation is a measure on the variability of a number set from its average. Since all numbers in your set are the same, there is no variation from its average, and the standard deviation is 0.

64 62 52 50 70 60 55 20 25 48 35 55 55 47 64 42 36 50 30 53 51 63 58 50 60 54 33 48 40 76 61 46 65 65 15 45 58 40 64 18 33 40 64 18 33 40 48 9 38 41

Highest value observed: 76
Lowest Value: 9
Standard deviation from the ungrouped data: 15.25
Frequency:
Mean: 46.94
Standard deviation from grouped data: 15.40

Jill. She scored two standard deviations above the mean, while he only scored one-and-a-half standard deviations above the mean.

M=500 and S=100 in a normal distribution, what percentage of the subjects have scores between 400 and 600

Mode - 2 - STAT - 1(VAR) Then put your data: 25,34,13

Then press AC which is the clear button and then SHIFT - 1(STAT) - 5(VAR) 2 (X) =

Voila!

I want to calculate a standard deviation on BA II plus

Standard deviation is the average root mean squared deviation from the average of the numbers.

Familiarize yourself with the wikipedia page on standard deviation: http://en.wikipedia.org/wiki/Standard_deviation

In this case, your question is easy. The standard deviation is 0, so this means the boys ages are all the same.

So they're all 24/3 = 8 years old.

Proof:
8 + 8 + 8 = 24 <-- satisfies the constraint that the boys ages must total to 24.

Get the standard deviation of these numbers;

8+8+8 / 3 = 8 <-- the average value is 8

The deviation of each boy's age from the average is:
boy 1
--------
8 years old, which deviates from 8 by 0
boy 2
--------
8 years old, which deviates from 8 by 0
boy 3
--------
8 years old, which deviates from 8 by 0

So the deviations are 0, 0 and 0.

To get the standard deviation, you sum the squares of the deviations of each boy, get the average, and square root. So:

0² + 0² + 0² = 0
Average is 0 / 3 = 0
Square root of 0 = 0

So the standard deviation is 0. Which shouldn't be much of a surprise to you. We just had to actually DO the work to show that it was in fact 0.

This calc will do standard deviations. In the manual it is on page 2 and also on page 40.