;in-circle?: num num num -> boolean
; - determine whether point is in circle
(define (in-circle? x y r)
   (<= (+ (sqr x) (sqr y)) (sqr r)))
 
 
#| Tests |#
(in-circle? 0 0 0)
"should be" true
(in-circle? 1 1 1)
"should be" false
(in-circle? 1 1 2)
"should be" true
 

;;new-price: Number Number -> Number
;; - produce discounted price based on weeks
(define (new-price price weeks)
  (cond
   [(< weeks 2) price]
   [(and (>= weeks 2) (< weeks 3)) (* price .75)]
   [(and (>= weeks 3) (< weeks 4)) (* price .50)]
   [else (* price .25)]))
 
 
#| Tests |#
(new-price 1 0)
"should be" 1
(new-price 1 2)
"should be" .75
(new-price 1 3)
"should be" .5
(new-price 1 5)
"should be" .25
 
 

;;pieces : Number Number -> Number
;; - given hour of day, compute pieces produced
(define (pieces hour workers)
  (cond
   [(and (>= hour 6) (< hour 10))
    (* workers 30)]
   [(and (>= hour 10) (< hour 14))
    (* workers 40)]
   [(and (>= hour 14) (< hour 18))
    (* workers 35)]))
 
(pieces 6 10)
"should be" 300
(pieces 10 10)
"should be" 400
(pieces 14 10)
"should be" 350
 

;;charge : Number Number -> Number
;; - given MB data transferred and base base, compute charges
(define (charge data base)
  (cond
   [(<= data 100) (* data base)]
   [(and (> data 100) (<= data 500))
    (* (+ (* base 1.33) .05) data)]
   [(and (> data 500) (<= data 1500))
    (* (+ (* base 1.44) .08) data)]
   [(> data 1500)
    (* (* base 2) data)]))
 
(charge 100 1)
"should be" 100
(charge 501 1)
"should be" 761.52
(charge 1501 1)
"should be" 3002
 

;;tax: Number -> Number
;; - return tax given income
(define (tax income)
  (+ (fed-tax income) (state-tax income)))
 
;;fed-tex: Number -> Number
;; - return federal tax given income
(define (fed-tax income)
  (cond
   [(<= income 35000) (* income .15)]
   [(and (> income 35000) (<= income 100000))
    (+ (* 35000 .15) (* (- income 35000) .25))]
   [(> income 100000)
    (+ (* 35000 .15) (* (- 100000 35000) .25) (* (- income 100000) .35))]))
 
 
;;state-tax: Number -> Number
;; - return state tax given income
(define (state-tax income)
  (cond
   [(<= income 50000) 0]
   [(> income 50000) (* .05 (- income 50000))]))
 
(fed-tax 35000)
"should be" 5250
(fed-tax 100000)
"should be" 21500
(fed-tax 200000)
"should be" 56500
 
(state-tax 50000)
"should be" 0
(state-tax 50001)
"should be" 0.05
 
(tax 35000)
"should be" 5250
(tax 75000)
"should be" 16500
(tax 100000)
"should be" 24000