generating random_numbers with different probability

[sajnam]

Hi,

I was wondering is it possible to use random_number generator, and assign different weights to the outcome. So for example, If I wanted it to generate either the number 1 or 2, but how could I tell it that the probability of generating 2 should be say 70%, and the probability of generating 1 is 30%. Then get it to run and see how many times I get the ans 1 and how many times I get 2. Like rolling a dice, only the probability of rolling one number over the others is greater.
Would appreciate anyones help with this.
Thank you.

 

[ArkM]

Obvious pseudocode (suppose frand returns 0..1 pseudo random numbers):

if frand() <= 0.7 then
   return 2
else
   return 1

See any book about applied math statistics...

 

[sajnam]

Thank you. Thats brilliant, and so simple.