(17B) Normal Distribution

[Eddie W. Shore]

Normal Distribution

The following solver approximates the area of a normal distribution. The following equation uses L (Let) and G (Get), so this can be used for the classic HP 17BII and the silver HP 17BII+.

Code:

NORM: CDF=1-EXP(-X^2÷2)÷SQRT(2*PI)*(.4361836*
L(T:INV(1+.33267*X))-.1201676*G(T)^2+.9372980*G(T)^3)

Instructions:

For x ≥ 0, enter x in ( X ) and then press (CDF) to solve.

For x < 0, enter abs(x) in ( X ), press (CDF) to solve, negate the result and add 1.

The area will be calculated from 0 (the center) to x.

Example 1: x = 2.5

2.5 (X), (CDF): Result: 0.99

Example 2: x = 1

1 (X), (CDF): Result: 0.84

Example 3: x = -1.5

(Algebric Mode)

1.5 (X), (CDF) [+/-] [ + ] 1 [ = ]: Result: 0.07

Source:

"Handbook of Mathematical, Scientific, and Engineering Formulas, Tables, Functions, Graphics, Transforms" Research & Education Association. 1984 ISBN 0-87891-521-4

Blog Entry: https://edspi31415.blogspot.com/2019/03/...andom.html