1-9-2.rkt~

;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-beginner-reader.ss" "lang")((modname 1-9-2) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f () #f)))
; A List-of-temperatures is one of: 
; – '()
; – (cons CTemperature List-of-temperatures)


(define ABSOLUTE0 -272)
; A CTemperature is a Number greater than ABSOLUTE0.


; List-of-temperatures -> Number
; computes the average temperature 
; List-of-temperatures -> Number
; computes the average temperature 
(define (average alot)
  (/ (sum alot) (how-many alot)))
 
; List-of-temperatures -> Number 
; adds up the temperatures on the given list 
(define (sum alot) 0)
 
; List-of-temperatures -> Number 
; counts the temperatures on the given list 
(define (how-many alot) 0)

(check-expect
  (average (cons 1 (cons 2 (cons 3 '())))) 2)