The first name in this array is Jack.

Detailed Answer

        
import java.util.Arrays;

public class Arrays {
    public static void main(String[] args) {

        String[] student_names = {"Jack", "Mike", "Katy", "Alice"};
        
        System.out.println("The first name in this array is " + student_names[0] + ".");
    }
}
        
    

The first name in this array is Katy with the grade 6.

Detailed Answer

        

public class Arrays {

    public static void main(String[] args) {

        String[] student_names = {"Katy", "Alice", "Jordan", "Jack", "Matt"};
        
        int[] student_grades = {6,6,5,4,7};
        
        System.out.println("The first name in this array is " + student_names[0] + " with the grade " + student_grades[0]);
        

    }

}
            
        
    

a) London, Paris, Amsterdam, Lisbon

b) Lisbon, Amsterdam, Paris, London

Detailed Answer

        
public class Arrays {

    public static void main(String[] args) {

        String[] cities = {"London", "Paris", "Amsterdam", "Lisbon"};
    
//		Part A
        for (int i = 0; i < cities.length; i++) {
            System.out.println(cities[i]);
        }
        
//		Part B
        for (int i = cities.length-1; i >= 0; i--) {
            System.out.println(cities[i]);
        }
}
}
        
    

The sum spent on all employees in a year is 132000.

The average monthly salary of all employees is 2200.

Detailed Answer

        
public class Arrays {

    public static void main(String[] args) {

        String[] employees = {"Alex", "Tom", "Scott", "Miley", "Jackson"};
        int[] salaries = {2200, 1900, 3300, 2150, 1450};
        int sum = 0;
        int sum2 = 0;
        
//		Part A
        for (int i = 0; i < salaries.length; i++) {
            sum = sum + (salaries[i] * 12);
        }
        
        System.out.println("The sum spent on all employees in a year is " + sum);
        
//		Part B
        for (int i = 0; i < salaries.length; i++) {
            sum2 = sum2 + salaries[i];
        }
        
        double average = (double) sum2 / salaries.length;
        System.out.println("The average monthly salary of all employees is " + average);

}
}
        
    

The average tax amount is 35.22 billion dollars.

Detailed Answer

        

public class Arrays {

    public static void main(String[] args) {
        
        String[] companies = {"Samsung", "HP", "Sony", "Bosch", "Siemens", "Apple"};
        double[] incomes = {220.1, 16.7, 215.4, 67.9, 31.2, 358.4};
        
        double sum = 0;
        double tax_rate = 0;
        
        for (int i = 0; i < incomes.length; i++) {
            
            if (incomes[i] < 1) {
                tax_rate = 0.12;
            }
            
            else if (incomes[i] >= 1 && incomes[i] < 50) {
                tax_rate = 0.15;
            }
            
            else if (incomes[i] >= 50 && incomes[i] < 100) {
                tax_rate = 0.2;
            }
            
            else {
                tax_rate = 0.24;
            }
            
            double tax_amount = incomes[i] * tax_rate;
            
            System.out.println(tax_amount);
            
            sum = sum + tax_amount;

        }
        
        double average_tax = (double) sum / incomes.length;
        System.out.println("The average tax rate for those companies is " + average_tax);     
}
}
        
    

There are 6 numbers divisible by 2 and 4 numbers divisible by 3.

Detailed Answer

        
public class Arrays {

    public static void main(String[] args) {

        int[] numbers = {2,3,7,8,5,10,12,45,34,12};
        int divTwo = 0;
        int divThree = 0;
        
        for (int i = 0; i < numbers.length; i++) {
            
            if (numbers[i] % 2 == 0) {
                divTwo = divTwo + 1;
            }
            
            if (numbers[i] % 3 == 0) {
                divThree = divThree + 1;
            }
            
        }
    
        System.out.println("There are " + divTwo + " numbers divisible by 2, and " + divThree + " numbers divisible by 3.");
        
}
}
        
    

The highest temperature of the week is 22.1°C.

The lowest temperature of the week is 14.8°C.

The average temperature of the week is 18.2°C. It was a warm week.

Detailed Answer

        
public class Arrays {
    public static void main(String[] args) {

        double[] temperatures = {15.5, 18.2, 19.8, 22.1, 20.5, 16.3, 14.8};
        
        double highest = 0;
        double lowest = 100000;
        
        
        for (int i = 0; i < temperatures.length; i++) {
            if (temperatures[i] > highest) {
                highest = temperatures[i];
            }
        }
        
        
        for (int i = 0; i < temperatures.length; i++) {
            if (temperatures[i] < lowest) {
                lowest = temperatures[i];
            }
        }
        
//    	Part A
        
        System.out.println("The highest temperature of the week is " + highest);
        System.out.println("The lowest temperature of the week is " + lowest);
        
        
//    	Part B
        
        double sum = 0;
        
        for (int i = 0; i < temperatures.length; i++) {
            sum = sum + temperatures[i];
        }
        
        double average = sum / temperatures.length;
        
        if (average > 18) {
            System.out.println("The average temperature of the week is " + average + ". It was a warm week.");
        }
        else {
            System.out.println("The average temperature of the week is " + average + ". It was a cool week.");
        }
        
    }
}
        
    

The product with the highest sales is Laptop.

The total sales across all products is 4901.5$.

Detailed Answer

        
public class Arrays {
    public static void main(String[] args) {

        String[] products = {"Laptop", "Headphones", "Monitor", "Mouse", "Keyboard"};
        double[] sales = {1200.0, 850.5, 1120.75, 750.0, 980.25};
        
        double highestSales = 0;
        String topProduct = "null";
        
        double sum = 0;
        
        
        for (int i =0; i < sales.length; i++) {
            if (sales[i] > highestSales) {
                highestSales = sales[i];
                topProduct = products[i];
            }
            
            sum = sum + sales[i];
        }
        
        System.out.println("The product with the highest sales is " + topProduct);
        System.out.println("The total sales across all products is " + sum);

        
    }
}
        
    

The student with the highest grade in Mathematics is Sue.

Total number of students with grades in Mathematics is 3.

Detailed Answer

        
public class Arrays {

    public static void main(String[] args) {
    
        int[] grades = {5,6,4,5,7,5,4};
        String[] subjects = {"English", "Mathematics", "English", "Biology", "Mathematics", "Chemistry", "Mathematics"};
        String[] students = {"John", "Alice", "Mark", "Tom", "Sue", "Mike", "Sarah"};
        
        int highest_grade = 0;
        String best_student = "null";
        int math_count = 0;
        
        for (int i = 0; i < grades.length; i++) {
            if (subjects[i].equals("Mathematics") && grades[i] > highest_grade) {
                highest_grade = grades[i];
                best_student = students[i];
            }
        }
        
        
        for (int i = 0; i < grades.length; i++) {
            if (subjects[i].equals("Mathematics")) {
                math_count++;
            }
        }
        
        System.out.println("The student with the highest grade in Mathematics is " + best_student + " with a grade of " + highest_grade);
        System.out.println("Total number of students with grades in Mathematics is " + math_count);
    }
}
        
    

The average of all odd numbers from this set is 9.4.

The odd numbers have a greater average, and they differ by 0.4.

Detailed Answer

public class Arrays {
    public static void main(String[] args) {

        int[] numbers = {2,4,5,1,8,11,13, 22,17};
        
        int sum_odd = 0;
        int count_odd = 0;
        
        for (int i = 0; i < numbers.length; i++) {
            if (numbers[i] % 2 != 0) {
                sum_odd = sum_odd + numbers[i];
                count_odd++;
            }
        }
        
//    	Part A 
        double average_odd = (double) sum_odd / count_odd;
        System.out.println("The average of all odd numbers from this set is " + average_odd);
        
        
//    	Part B 
        
        int sum_even = 0;
        int count_even = 0;
        
        
        for (int i = 0; i < numbers.length; i++) {
            if (numbers[i] % 2 == 0) {
                sum_even = sum_even + numbers[i];
                count_even++;
            }
        }
        
        
        double average_even = (double) sum_even / count_even;
        
        
        
        if (average_even > average_odd) {
            double difference = average_even - average_odd;
            System.out.println("The even numbers have a greater average, and they differ by " + difference);
        }
        
        else if (average_even < average_odd) {
            double difference = average_odd - average_even;
            System.out.println("The odd numbers have a greater average, and they differ by " + difference);
        }
        
        else {
            System.out.println("Their averages are the same");
        }

    }
}