• Complete the following function definition:

      ;; add-tax : Number -> Number 
      ;; add the sales tax to a given amount; 
      ;; assume the sales tax rate is 5%
      (define (add-tax net-amount)
    
    
    
    
        )
    
    
      ;; Examples/tests: 
      (equal? (add-tax 100) 105)
      (equal? (add-tax 200) 210)
    

    Solution:

    ;; [PT 1] for one of these (or equivalent): 
      (* 1.05 net-amount) 
    or 
      (+ net-amount (* .05 net-amount)) 
    

  • What will DrScheme's Interactions Window show when you run this complete program:

      (define NAME "Matthias")
    
      ;; closing : String -> String 
      ;; create a closing for a letter,
      ;; given the closing phrase 
      (define (closing txt) (string-append txt " \n" NAME))
    
      (string=? (closing "Sincerely")
                "Sincerely \nMatthias")
      ;; one could also test, but I won't:
      ;; (string=? (closing "Regards,")
      ;;           "Regards, \nMatthias")
    

    Solution: true ;; [PT 1]