Thursday, July 30, 2009

How to write this java program (dice, probability)?

HELP! Please!!!


When you are rolling a six-side dice that has numbers 1 through 6, the odds of you getting any particular number should be the same, in theory, that is 0.17, or 1/6. Let’s how good Math.random()is for simulating rolling a dice. Write a program to do the following:


a.


Generate N random numbers in between 1 and 6, inclusive. You can either ask for user input for N or hardcode a literal value.


b.


Calculate the probability of getting a 4 using the following formula:


probability = number of 4s / N


c.


Prints out the probability.

How to write this java program (dice, probability)?
This isn't the prettiest code, but it should help:





int target_number = 4;


int target_number_count = 0;


int trials = 1000;


for (int i = 0; i %26lt; trials; i++) {


    int random = (int) (Math.random() * 6) + 1;


    if (random == target_number) {


        target_number_count++;


    }


}





double expected_percentage = 1.0 / 6;


double actual_percentage = (float) target_number_count / trials;





System.out.println("I ran " + trials + " runs of Java's random number generator, looking for the number'" + target_number + "'");





System.out.println("I expected to see " + (trials / 6) + " instances of that number (" + expected_percentage + "%)");





System.out.println("I actually saw " + target_number_count + " instances of that number (" + actual_percentage + "%)");

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