Chapter 2 Exercise 21, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

*2.21 (Financial application: calculate future investment value) Write a program that reads in investment amount, annual interest rate, and number of years, and displays the future investment value using the following formula: futureInvestmentValue = investmentAmount * (1 + monthlyInterestRate)numberOfYears*12 For example, if you enter amount 1000, annual interest rate 3.25%, and number of years 1, the future investment value is 1032.98. Here is a sample run:

import java.util.Scanner;
 
public class ProgrammingEx2_21 {
 
 public static void main(String[] args) {
  Scanner input = new Scanner(System.in);
 
  System.out.print("Enter investment amount:");
  double investmentAmount = input.nextDouble();
  System.out.print("Enter annual interest rate in percentage:");
  double monthlyInterestRate = input.nextDouble();
  monthlyInterestRate = monthlyInterestRate / 12;
  System.out.print("Enter number of years:");
  double numberOfYears = input.nextDouble();
  double futureInvestmentValue = investmentAmount
    * Math.pow((1 + monthlyInterestRate / 100),
      (numberOfYears * 12));
  System.out.print("Accumulated value is " + futureInvestmentValue);
 
 }
 
}

Chapter 2 Exercise 20, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

*2.20 (Financial application: calculate interest) If you know the balance and the annual percentage interest rate, you can compute the interest on the next monthly payment using the following formula: interest = balance * (annualInterestRate/1200) Write a program that reads the balance and the annual percentage interest rate and displays the interest for the next month. Here is a sample run:

import java.util.Scanner;
 
public class ProgrammingEx2_20 {
 
 public static void main(String[] args) {
  Scanner input = new Scanner(System.in);
 
  System.out.print("Enter balance and interest rate (e.g., 3 for 3%):");
  double balance = input.nextDouble();
  double annualInterestRate = input.nextDouble();
  double interest = balance * (annualInterestRate/1200);
  System.out.print("The interest is " + interest);
 
 }
 
}

Chapter 2 Exercise 19, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

*2.19 (Geometry: area of a triangle) Write a program that prompts the user to enter three points  (x1, y1) , (x2, y2) , (x3, y3) of a triangle and displays its area. The formula for computing the area of a triangle is:

import java.util.Scanner;
 
public class ProgrammingEx2_19 {
 
 public static void main(String[] args) {
  Scanner input = new Scanner(System.in);
 
  System.out.print("Enter three points for a triangle:");
  double x1 = input.nextDouble();
  double y1 = input.nextDouble();
  double x2 = input.nextDouble();
  double y2 = input.nextDouble();
  double x3 = input.nextDouble();
  double y3 = input.nextDouble();
 
  double side1 = Math.sqrt(Math.pow(x1 - x2, 2) + Math.pow(y1 - y2, 2));
  double side2 = Math.sqrt(Math.pow(x2 - x3, 2) + Math.pow(y2 - y3, 2));
  double side3 = Math.sqrt(Math.pow(x1 - x3, 2) + Math.pow(y1 - y3, 2));
  double s = (side1 + side2 + side3) / 2;
  double area = Math.sqrt(s * (s - side1) * (s - side2) * (s - side3));
 
  System.out.print("The area of the triangle is  " + area);
 
 }
}

Chapter 2 Exercise 18, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

(Print a table) Write a program that displays the following table. Cast floating point numbers into integers.
a b pow(a, b)
1 2 1
2 3 8
3 4 81
4 5 1024
5 6 15625

public static void main(String[] args) {
   System.out.println("a   b   pow(a, b)");
   System.out.println("1   2   " + (int)Math.pow(1, 2));
   System.out.println("2   3   " + (int)Math.pow(2, 3));
   System.out.println("3   4   " + (int)Math.pow(3, 4));
   System.out.println("4   5   " + (int)Math.pow(4, 5));
   System.out.println("5   6   " + (int)Math.pow(5, 6));
}

Chapter 2 Exercise 17, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

*2.17 (Science: wind-chill temperature) How cold is it outside? The temperature alone is not enough to provide the answer. Other factors including wind speed, relative humidity, and sunshine play important roles in determining coldness outside. In 2001, the National Weather Service (NWS) implemented the new wind-chill temperature to measure the coldness using temperature and wind speed. The formula is [Math Processing Error]${\displaystyle twc=35.74+0.6215\cdot ta-35.75\cdot v^{0.16}+0.4275ta\cdot v^{0.16}}$ where ta is the outside temperature measured in degrees Fahrenheit and v is the speed measured in miles per hour. twc is the wind-chill temperature. The formula cannot be used for wind speeds below 2 mph or temperatures below -58 ºF or above 41ºF. Write a program that prompts the user to enter a temperature between -58 ºF and 41ºF and a wind speed greater than or equal to 2 and displays the wind-chill temperature. Use Math.pow(a, b) to compute [Math Processing Error]${\displaystyle v^{0.16}}$. Here is a sample run:

Enter the temperature in Fahrenheit between -58°F and 41°F:5.3
Enter the wind speed (>=2) in miles per hour: 6
The wind chill index is -5.56707 

import java.util.Scanner;
 
public class ProgrammingEx2_17 {
 
 public static void main(String[] args) {
  Scanner input = new Scanner(System.in);
 
  System.out
    .print("Enter the temperature in Fahrenheit between -58?F and 41?F:");
  double ta = input.nextDouble();
  System.out.print("Enter the wind speed (>=2) in miles per hour:");
  double v = input.nextDouble();
  double twc = 35.74 + 0.6215 * ta - 35.75 * Math.pow(v, 0.16) + 0.4275
    * ta * Math.pow(v, 0.16);
 
  System.out.print("The wind chill index is " + twc);
 
 }
}

Chapter 2 Exercise 16, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

2.16 (Geometry: area of a hexagon) Write a program that prompts the user to enter the
side of a hexagon and displays its area. The formula for computing the area of a
hexagon is 

where s is the length of a side. Here is a sample run:
    
    Enter the side: 5.5
    The area of the hexagon is 78.5895

import java.util.Scanner;
 
public class ProgrammingEx2_16 {
 
 public static void main(String[] args) {
  Scanner input = new Scanner(System.in);
 
  System.out.print("Enter the side:");
  double s = input.nextDouble();
  double area = (3 * Math.sqrt(3) / 2) * Math.pow(s, 2);
  System.out.print("The area of the hexagon is " + area);
 
 }
 
}

Chapter 2 Exercise 15, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

2.15 (Geometry: distance of two points) Write a program that prompts the user to enter two points (x1, y1) and (x2, y2) and displays their distance between them. The formula for computing the distance is √(x2-x1)2+(y2-y1)2 Note that you can use Math.pow(a, 0.5) to compute 2a. Here is a sample run:
Enter x1 and y1: 1.5 -3.4
 Enter x2 and y2: 4 5
The distance between the two points is 8.764131445842194

import java.util.Scanner;
 
public class ProgrammingEx2_15 {
 
 public static void main(String[] args) {
 
  Scanner input = new Scanner(System.in);
 
  System.out.print("Enter x1 and y1:");
  double x1 = input.nextDouble();
  double y1 = input.nextDouble();
  System.out.print("Enter x2 and y2:");
  double x2 = input.nextDouble();
  double y2 = input.nextDouble();
  double distance = Math.sqrt(Math.pow((x2 - x1), 2)
    + Math.pow((y2 - y1), 2));
  System.out.print("The distance between the two points is  " + distance);
 
 }
}