# Normal Distribution Casio Fx- 9750Gii

### #1

Posted 01 March 2015 - 08:37 PM

Thank you in advance for your time and expertise.

### #2

Posted 02 March 2015 - 09:37 AM

I assume you know the probability and mean or probability and standard deviation and the t-value is normalized.

You can choose from following methods:

1. spreadsheet calculations (brute force)

2. getting value from graph

3. getting value from handbook(s)

ad 1) this method consists in numerical calculations of probability based on t-value (Casio user's guide or x/u-value in hanbooks). Put the t-value in the first column, calculate the f(t) and use e.g. the trapezoidal rule to obtain the probability value. Compare the probability, find the proper t-value. By knowing t-value and mean or t-value and standard deviation you can calculate the non-normalized value (see the casio user's guide)

ad3) see the user's guide, page 6-20. You need to enter t-value only

ad3) You find the probability in the hanbooks and read the corresponding t-value. The following calculations is the same as in method 1.

__ Edited__: You can use the built-in solver. Go to EQUA menu, press F3 (Solver) and input the equation

A=1/sqrt(2pi)*int(e^-(X^2/2),0,T) and press enter.

A- the probability value

X- variable

T- t-value

sqrt - square root symbol (shift + x^2)

int - integration symbol, available via optn-calc

fill the probabilty value to A, leave the X as 0 and put the cursor on T and press F6 (solv). This settings corresponds to Q(t)

But remember, the A must be from interval (0;0.5).

With same procedure you can calculate mean or standard deviation. Just type the equation, fill the known values and solve the equation.

**Edited by pan.gejt, 03 March 2015 - 08:19 AM.**

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