13. Intro Exercises 3

1. (a) Write a check-expect for (question-1? 10 20). (b) Are there any inputs that will cause an error? Explain why or why not.

(define (question-1? x y)
  (and (= 1/2 (/ x y))
       (not (= y 0))))

2. Simplify and identify any errors:

(define (question-2? boat-sinking? have-lifejackets?)
  (or (boolean=? boat-sinking? false)
      have-lifejackets?)

3. Simplify and identify any errors:

(define (eat-cheap? hungry? money mcburger?)
  (and (> money 1) hungry? (< money 20)
       (or mcburger? (not mcburger?))))

4. Write the function before-water?: string -> boolean that takes in a string and determines if the string appears before the word “water” in the dictionary.

5. Write the function bookends?: string -> boolean that takes in a string and produces true if the string appears before “book” or after “end” in the dictionary.

6. Write a function avoids-yellow?: image -> boolean that is true if the image is neither a yellow square nor a yellow circle.