in java$4\mathrm{.}17($Gas Mileage$)$ Drivers are concerned with the mileage their automobiles get. One driver has kept track of several trips by recording the miles driven and gallons used for each tankful$.$ Develop a Java application that will input the miles driven and gallons used $($both as integers$)$ for each trip. The program should calculate and display the miles per gallon obtained for each trip and print the combined miles per gallon obtained for all trips up to this point. All averaging calculations should produce floating$-$point results. Use class Scanner and sentinel$-$controlled iteration to obtain the data from the user.

$4\mathrm{.}18($Credit Limit Calculator$)$ Develop a Java application that determines whether any of several department$-$store customers has exceeded the credit limit on a charge account. For each customer, the following facts are available:

account number

balance at the beginning of the month

total of all items charged by the customer this month

total of all credits applied to the customer$$s account this month

allowed credit limit$.$

The program should input all these facts as integers, calculate the new balance $(=$ beginning balance $+$ charges $$ credits$),$ display the new balance and determine whether the new balance exceeds the customer$$s credit limit$.$ For those customers whose credit limit is exceeded, the program should display the message "Credit limit exceeded".

$4\mathrm{.}19($Sales Commission Calculator$)$ A large company pays its salespeople on a commission basis. The salespeople receive $$200$ per week plus $9\%$ of their gross sales for that week. For example, a salesperson who sells $$5,000$ worth of merchandise in a week receives $$200$ plus $9\%$ of $$5,000,$ or a total of $$650.$ You$$ve been supplied with a list of the items sold by each salesperson. The values of these items are shown in Fig. $4\mathrm{.}33.$ Develop a Java application that inputs one salesperson$$s items sold for last week and calculates and displays that salesperson$$s earnings. There$$s no limit to the number of items that can be sold.

Fig. $4\mathrm{.}33$

Item Value

$1239\mathrm{.}99$

$2129\mathrm{.}75$

$399\mathrm{.}95$

$4350\mathrm{.}89$

Item values for Exercise $4\mathrm{.}19.$

$4\mathrm{.}20($Salary Calculator$)$ Develop a Java application that determines the gross pay for each of three employees. The company pays straight time for the first $40$ hours worked by each employee and time and a half for all hours worked in excess of $40.$ You$$re given a list of the employees, their number of hours worked last week and their hourly rates. Your program should input this information for each employee, then determine and display the employee$$s gross pay. Use class Scanner to input the data.

$4\mathrm{.}21($Find the Largest Number$)$ The process of finding the largest value is used frequently in computer applications. For example, a program that determines the winner of a sales contest would input the number of units sold by each salesperson. The salesperson who sells the most units wins the contest. Write a pseudocode program, then a Java application that inputs a series of $10$ integers and determines and prints the largest integer. Your program should use at least the following three variables:

counter: A counter to count to $10($i$.$e$.,$ to keep track of how many numbers have been input and to determine when all $10$ numbers have been processed$).$

number: The integer most recently input by the user.

largest: The largest number found so far.

$4\mathrm{.}22($Tabular Output$)$ Write a Java application that uses looping to print the following table of values:

N $10*$N $100*$N $1000*$N

$1101001000$

$2202002000$

$3303003000$

$4404004000$

$5505005000$

$4\mathrm{.}23($Find the Two Largest Numbers$)$ Using an approach similar to that for Exercise $4\mathrm{.}21,$ find the two largest values of the $10$ values entered. $[$Note: You may input each number only once.$]$

$4\mathrm{.}24($Validating User Input$)$ Modify the program in Fig. $4\mathrm{.}12$ to validate its inputs. For any input, if the value entered is other than $1$ or $2,$ keep looping until the user enters a correct value.

$4\mathrm{.}25$ What does the following program print?

$1//$ Exercise $4\mathrm{.}25$: Mystery$2.$java

$2$ public class Mystery$2\{$

$3$ public static void main$($String$[]$ args$)\{$

$4$ int count $=1$;

$5$

$6$ while $($count $<=10)\{$

$7$ System.out.println$($count $\%2==1?"****"$ : $"++++++++")$;

$8++$count;

$9\}$

$10\}$

$11\}$

$4\mathrm{.}26$ What does the following program print?

$1//$ Exercise $4\mathrm{.}26$: Mystery$3.$java

$2$ public class Mystery$3\{$

$3$ public static void main$($String$[]$ args$)\{$

$4$ int row $=10$;

$5$

$6$ while $($row $>=1)\{$

$7$ int column $=1$;

$8$

$9$ while $($column $<=10)\{$

$10$ System.out.print$($row $\%2==1?"<"$ : $">")$;

$11++$column;

$12\}$

$13$

$14--$row;

$15$ System.out.println$()$;

$16\}$

$17\}$

$18\}$

$4\mathrm{.}27($Dangling$-$else Problem$)$ The Java compiler always associates an else with the immediately