exam3.1.1-exam3.1.4

;; mht created on Nov 8, 2011

;; profit : number number -> number
;; to compute the profit as the difference between revenue and costs at some given ticket-price
;; example : (profit 5) should be (- 600 184.8)
(define (profit ticket-price)
  (- (revenue ticket-price)
     (costs ticket-price)))

;; revenue : number -> number
;; to compute the revenue given ticket-price
;; example : (revenue 5) should be (* 5 120)
(define (revenue ticket-price)
  (* ticket-price
     (attendees ticket-price)))

;; costs : number -> number
;; to compute the costs given ticket-price
;; example : (costs 5) should be (+ 180 (* 120 0.04))
(define (costs ticket-price)
  (+ 180 (
          * .04 (attendees ticket-price))))

;; attendees : number -> number
;; to compute the number of attendees, given ticket-price
;; example : (attendees 5) should be 120
;; (attendees 3) should be 420
;; (attendees 4) should be 270
(define (attendees ticket-price)
  (+ 120
     (* (/ 15 .10) (- 5.00 ticket-price))))

;; test:
(attendees 4)
(costs 5)
(profit 3)
(profit 4)
(profit 5)

;; new-costs: number -> number
;; to compute the costs given ticket-price
;;
(define (new-costs ticket-price)
  (* 1.54 (attendees ticket-price)))
;; test
;(new-costs 5)


;; new-profit
(define (new-profit ticket-price)
  (- (revenue ticket-price)
     (new-costs ticket-price)))

(new-profit 3)
(new-profit 4)
(new-profit 5)