Jump to content

- - - - -

Normal Distribution Casio Fx- 9750Gii

  • Please log in to reply
1 reply to this topic

#1 Fern



  • Members
  • Pip
  • 1 posts
  • Gender:Female
  • Interests:Physics, ballet, maths, reading, history.

  • Calculators:
    Casio fx-9750gii
    Casio fx-GT x2

Posted 01 March 2015 - 08:37 PM

I have found how to get either the probability or value of normally distributed data by entering the mean and standard deviation but I was wondering if there was any way to get the mean/ standard deviation from the probability and value for my S1 exam. Sorry I haven't explained very clearly.
Thank you in advance for your time and expertise.

#2 pan.gejt


    Casio Freak

  • Members
  • PipPipPipPip
  • 112 posts
  • Gender:Male
  • Location:CZ

  • Calculators:
    fx-880, fx-6300G, fx-9700GE, fx-9860G Slim, Classpad 330-A, TI-Nspire + keypad, TI-Nspire CAS, TI-Nspire CX CAS,TI-89 Titanium, HP-50g, SEC-101, fx-991ES PLUS, fx-991DE PLUS, fx-CP400, Canon X MARK I PRO, Citizen SRP-75,

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.

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users