$1.$ Write a method in the Gradebook class $($from DF#$1)$ that finds the minimum score of all students.

$2.$ Write a method in the Gradebook class $($from DF#$1)$ that finds the maximum score of all students.

$3.$ Write a Java static method that receives a String as its input parameter and returns true if the given string represents an integer from $0$ to $100.$ The method returns false otherwise.

$4.$ Write a Java static method that receives a String as its input parameter and returns true if the given string represents a valid $7-$digit Panther ID$.$ The method returns false otherwise.

$5.$ Predict the outcome of the following program:

class A$\{$

int x;

int decreaseCounter$()\{$

return $--$x;

$\}$

A $($int x$)\{$

this.x $=$ x;

$\}$

$\}$

public class B extends A$\{$

private int y;

private int increaseCounter$()\{$

return $++$y;

$\}$

public B$($int x$,$ int y$)\{$

super$($x$)$;

this.y $=$ y;

$\}$

public static void main$($String$[]$ args$)\{$

B b $=$ new B$(10,20)$;

b$.$increaseCounter$()$;

b$.$decreaseCounter$()$;

System.out.printf$("\%$d$,\%$d$",$ b$.$x$,$ b$.$y$)$;

$\}$

$\}$

$6.$ Predict the output of the following program:

class A$\{$

A $()\{$

System.out.println$("$A$")$;

$\}$

$\}$

class B extends A$\{$

public B$()\{$

System.out.println$("$B$")$;

$\}$

$\}$

public class C extends B$\{$

public C$()\{$

System.out.println$("$C$")$;

$\}$

public static void main$($String$[]$ args$)\{$

C c $=$ new C$()$;

$\}$

$\}$