The following checksum formula is widely used by banks and credit card companies to validate legal account numbers: d0 + f(d1) +
1 answer:
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Answer:
Here is the corrected program:
import java.util.Scanner; //to accept input from user
public class 02_14_Activity_one { //class name
public static void main(String[] args) { //start of main method
Scanner scan = new Scanner(System.in); //creates Scanner class object
System.out.println("Enter first string"); //prompts user to enter first string
String s1 = scan.nextLine(); //reads input string from user
System.out.println("Enter second string"); //prompts user to enter second string
String s2 = scan.nextLine(); //reads second input string from user
System.out.println("Enter number of letters from each word"); //enter n
int n = scan.nextInt(); //reads value of integer n from user
System.out.println(s1.substring(0,n) + s2.substring(s2.length() - n ));
} } //uses substring method to print a string made up of the first n letters of s1 and the last n letters of s2.
Explanation:
The errors were:
1.
Scanner scan = Scanner(System.in);
Here new keyword is missing to create object scan of Scanner class.
Corrected statement:
Scanner scan = new Scanner(System.in);
2.
String s1 = nextLine();
Here object scan is missing to call nextLine() method of class Scanner
Corrected statement:
String s1 = scan.nextLine();
3.
String s2 = Scanner.nextLine();
Here class is used instead of its object scan to access the method nextLine
Corrected statement:
String s2 = scan.nextLine();
4.
String n = scan.nextLine();
Here n is of type String but n is a whole number so it should be of type int. Also the method nextInt will be used to scan and accept an integer value
Corrected statement:
int n = scan.nextInt();
5.
System.out.println(s1.substring(1,n-1) + s2.substring(s1.length()-n));
This statement is also not correct
Corrected statement:
System.out.println(s1.substring(0,n) + s2.substring(s2.length() - n ));
This works as follows:
s1.substring(0,n) uses substring method to return a new string that is a substring of this s1. The substring begins at the 0th index of s1 and extends to the character at index n.
s2.substring(s2.length() - n ) uses substring method to return a new string that is a substring of this s2. The substring then uses length() method to get the length of s2 and subtracts integer n from it and thus returns the last n characters of s2.
The screenshot of program along with its output is attached.
Answer:
<u>The total time elapsed from the time a bit is created (from the original analog signal at Host A) until the bit is decoded (as part of the analog signal at Host B is </u><u>25.11 ms</u>
Explanation:
Host A first converts the analog signal to a digital 64kbps stream and then groups it into 56-byte packets. The time taken for this can be calculated as:
time taken 1=
= (56 x 8) bits / 64 x 10³ bits/s
= 7 x 10⁻³s
time taken 1= 7 ms
The transmission rate of the packet from Host A to Host B is 4 Mbps. The time taken to transfer the packets can be calculated as:
time taken 2= (56 x 8) bits / 4 x 10⁶ bits/s
= 1.12 x 10⁻⁴ s
time taken 2= 112 μs
The propagation delay is 18 ms.
To calculate the total time elapsed, we need to add up all the time taken at each individual stage.
<u /><u> = Time taken 1 + Time taken 2 + Propagation Delay</u>
= 7 ms + 112 μs + 18 ms
= 0.025112 s
= 25.11 ms