A particullar System is Controlled by an operator through commands entered from keyboard. The average number of Commands entered in an $12$ hour interval is $4000.$

a$)$ Suppose the Processor Scans the keybord evey $400$ ms$.$How many times will the keyboard be checked in an $12-$hour's period $2$

$5)$ By what Fraction would of processor visits to the keyboard be reduced if interrupt$-$ driven I$/0($Input$/$output$)$ were used?