solve.php

#!/usr/bin/env php
<?php
/**
* This script solves the problem posted at https://www.facebook.com/hserus/posts/10209365831889209
*
* If you choose an answer to this question at random, what is the chance you will be correct?
*
* A) 25%
* B) 50%
* C) 60%
* D) 25%
*
*/


/**
* Run the odds, and see if we're correct or not.
*/
function run($odds) {

	$retval = array();
	$correct = false;

	//
	// Pick a random question, and get that percentage chance.
	//
	$index = mt_rand(0, 3);
	$chance = $odds[$index];

	//
	// Now create a random percentage, and if it's less than the chance,
	// we're correct!
	//
	$roll = mt_rand(0, 99);
	if ($roll < $chance) {
		$correct = true;
	}

	$retval["index"] = $index;
	$retval["letter"] = chr(65 + $index);
	$retval["chance"] = $chance;
	$retval["roll"] = $roll;
	$retval["correct"] = $correct;

	return($retval);

} // End of run()


/**
* Our main entry point.
*/
function main($num_guesses) {

	//
	// Our group of odds by percentage
	//
	$odds = array(25, 50, 60, 25);

	$num_correct = 0;

	for ($i=0; $i<$num_guesses; $i++) {

		$results = run($odds);
		//printf("Guess: %s, Chance: %d, Roll: %d, Correct?: %s\n", 
		//	$results["letter"], $results["chance"], $results["roll"], $results["correct"]);

		if ($results["correct"]) {
			$num_correct++;
		}

	}

	printf("Correct rate: %d / %d\n", $num_correct, $num_guesses);
	printf("Chance of a correct answer: %.2f%%\n", ( $num_correct / $num_guesses ) * 100 );

} // End of main()


main(1000000);