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[giddy]

hi,

I did try searching my question but I found solutions for different calculator models which dont work on my calc. I have a Casio fx 911 MS and I want how if it is possible to calculate the normal distribution for a P(X=x) where X ~ N(0,1) ? (Im doing A level maths with stats 1 and 2)

Thanks
Gideon

[JimC]

I have a Casio fx 911 MS and I want how if it is possible to calculate the normal distribution for a P(X=x) where X ~ N(0,1) ?

You could calculate this directly with numerical integration. The function P(t) is the integral of the standard normal distribution from negative infinity to t. I believe the fx-911MS does have the numerical integration function. The function you need to integrate is 1/sqrt(2*pi) * e^-(t^2/2). Call this function F(t) for the probability density function.

Then to calculate the cumulative probability, and I substitute the value -8 for negative infinity, use this formula:

P(t) = Integral from -infinity to t of : F(t)

You can also go to my MediaFire download page for the Scientific Calculator Comparison I've written. Look for Casio Sharp Vol 2 and goto Appendix J where the formulas are given for calculating the areas under the normal curve for P(t), Q(t), and R(t). There are suggestions also for improving accuracy.

I usually opt to calculate the integral directly since this function is notoriously difficult to estimate, most people already know the density function F(t), and integration is pretty quick on these calculators.

Hope this helps,
JTCullen

Edited by JimC, 01 July 2010 - 09:44 AM.