Setting probability of getting a random number 1 or 2

Question

Is there a way to set a probability control on getting a random value either 1 or 2? Suppose if I want more than 70% of the time it should be 1 and only 30% should be the chance of getting 2 in rand(1,2). Is it possible?

Possible duplicate of [Generate random numbers with fix probability](http://stackoverflow.com/questions/21572363/generate-random-numbers-with-fix-probability) — Shogunivar, Mar 29 '17 at 11:38

score 0 · Accepted Answer · answered Mar 29 '17 at 11:40

0

Generate a number between 1 and 10, then if the number is greater than 7, return 2, else return 1

x = rand(1, 10);
if(x > 7){
    return 2;
}
else {
    return 1;
}

You will have 70% and 30% of chance to get the number you want

answered Mar 29 '17 at 11:40

Thomas Rbt

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that's a perfectly simple trick.. exactly matching my query.. thank you :) – Mar 29 '17 at 12:46

score 0 · Answer 2 · answered Mar 29 '17 at 11:41

0

Why don't you generate a uniformly distributed random number and then filter the number with an if?

int x,r;

r=rand() % 100;         // r in the range 0 to 99
if(r<=70){x=1;}
else{x=2;}

answered Mar 29 '17 at 11:41

Francisco Herrerias-Azcue

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score 0 · Answer 3 · answered Mar 29 '17 at 11:42

0

This should do the trick:

function yourrand($prob) {
      $r = rand();
      if ($r < $prob) { return 1; }
      else { return 2; }
}

answered Mar 29 '17 at 11:42

Pedro Cipriano

13
7

Setting probability of getting a random number 1 or 2

3 Answers3