# Tutoring Math Foundations 11, standard deviation is front and centre right now. The tutor continues explaining the standard deviation function on various scientific calculators.

Like the Sharp EL-520W, the Casio fx-260Solar requires you to set the mode to use its standard deviation function. On the Casio, it’s MODE . (mode, then decimal point). What I like is that the Casio has the modes printed just under the screen. Look and you’ll see, in blue, . SD. Of course, SD refers to Standard Deviation.

**Example: Calculate the standard deviation of the number set {-18,16,0,45,100,32,27}.**

**Solution:** As mentioned above, key in MODE . to get in SD mode. Then, you should see SD in the upper right corner.

To enter the numbers, you use the M+ key at the bottom right. In SD mode, it becomes the DATA key. Look underneath it; you’ll see DATA printed in blue.

To input -18, you actually have to enter 18 first, *then* +/-. Reason: the Casio fx-260Solar is reverse-entry.

Input -18 M+, 16 M+ and so on. Unlike the Sharp EL-520W, the Casio fx-260Solar does not give you feedback as it accepts the data.

Reaching the end of our list, we key in 27 M+. It’s time to find the standard deviation. Key in SHIFT 8 to get σ_{n}. You should get 34.9, which is of course what we got with the Sharp EL-520W. After all, the data set is the same. To get σ_{n-1}, key in SHIFT 9. I believe that Foundations 11 prefers σ_{n}.

To clear the statistical data before entering a new list, change the mode to COMP by pressing MODE 0, then press MODE . to get back into SD mode. Changing out of SD mode, then back into it, seems to clear the previous list.

The mode for ordinary use is COMP. Once again: to return to COMP mode, press MODE 0

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.