Unit 4A - Free Response - Number Cube A

Unit 4A - Free Response - Number Cube A

Each coding exercise has its own folder. Open its .java file and press Run to try it. Run Tests checks every graded exercise in this lesson at once.

The following is a free response question from 2009. It was question 1 on the exam. You can see all the free response questions from past exams at Past AP CSA Exams.

Question 1. A statistician is studying sequences of numbers obtained by repeatedly tossing a six-sided number cube. On each side of the number cube is a single number in the range of 1 to 6, inclusive, and no number is repeated on the cube. The statistician is particularly interested in runs of numbers. A run occurs when two or more consecutive tosses of the cube produce the same value. For example, in the following sequence of cube tosses, there are runs starting at positions 1, 6, 12, and 14.

public class NumberCube
{
    /**
     * @return an integer value between 1 and 6, inclusive
     */
    public int toss()
    {
        /* implementation not shown */
    }

    // There may be instance variables, constructors, and methods not shown.
}

Part a. Write the method getCubeTosses that takes a number cube and a number of tosses as parameters. The method should return an array of the values produced by tossing the number cube the given number of times.

How to Solve

You will need to create an array to hold the results of each cube toss. The size of the array should be the passed number of times you will call toss. You will need to loop that number of times and each time set the value of the array at that index to the result of the toss. Return the array.

Check your understanding: Which Java expression correctly generates a random number between 1 and 6? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/numberCubeA.html#numbercubea_1

Check your understanding: Which of the following correctly creates an array of size numTosses? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/numberCubeA.html#numbercubea_2

Check your understanding: Which of the following correctly loops numTosses number of times? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/numberCubeA.html#numbercubea_3

Mixed Up Code

Check your understanding: The method getCubeTosses below contains the correct code for one solution to this problem, but it is mixed up. — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/numberCubeA.html#numcubeA

Try and Solve Part A

Exercise 1

FRQ Number Cube A: Write the method getCubeTosses that takes a number cube and a number of tosses as parameters. The method should return an array of the values produced by tossing the number cube the given number of times.

Open the 01-FRQNumberCubeA folder and edit NumberCube.java. Press Run to try it; Run Tests checks it (4 tests).