# Binomial Distributions

#### rkslperez

##### New Member
Hello there,

Finally got the hang of the this from by using my Excel. Although, I would love to do it on my Ti86 and by the formula method.

problems: 1) I cant seem to find the Binomial Dist funciton in my Ti-86, does anyone know where in the calculator it is. (already tried looking it online, in book...and I know..everyone hates the Ti-86 but its all I have to work it)

so when that doesnt work.. I would like to do it by hand but the formula...scary...

2) Im not sure what goes where. For example: Survery indicates hat 41% of women in the US consider reading as their favorite pass time. Randomly select 4 women and ask them if this is true. Find the probabliblity the (1) exactly 2 say yes (2) at least two say yes and (3) fewer then two say yes.

Here is what I gathered:

n=4
p=.41
q=.59
(1) x=2 (2) x=0,1,2 (3) x=0,1

now the formula for (1)

p(2)=4C2(.41)^2(.59)^2 = 6(.41)^2(.59)^2 = apprx. .351

okokok...what the heck is the C ?? in my book the 4 & 2 are subscript. and then how to the 4C2 equal 6? is this some 'log' thing?

help with the calculator or equation would set me in the right direction.. thanks for guiding me along

Kelly

E

#### elnaz

##### Guest
hello
why dont you compute aCb by hand ?
it is not scary at all,
aCb= a!/[b!*(b-a)!] a!=a*(a-1)*(a-2)*...*2*1
i sure , you know about factorial so you can compute 4C2 now
4C2=4!/[2!*2!]=[1*2*3*4]/[1*2*1*2]=6