Mine

;; Question 4

(define-struct clock (hour min sec))

(define (addHour clk)
   (cond
     [(> (+ (clock-hour clk) 1) 12) 0]
     [else (+ (clock-hour clk) 1)]
   )
)

(define (addMin clk)
   (cond
     [(> (+ (clock-min clk) 1) 59) (addHour clk)]
     [else (+ (clock-hour clk) 1)]
   )
)

(define (addSec clk) 
   (cond
     [(> (+ (clock-sec clk) 1) 59) (addMin clk)]
     [else (+ (clock-sec clk) 1)]
   )
)

(define (tick clk)
  (make-clock (addHour clk) (addMin clk) (addSec clk))
)