;; SICP 3.1.2.

(define (estimate-pi trials)
  (sqrt (/ 6 (monte-carlo trials cesaro-test))))

(define (cesaro-test)
  (= (gcd (random) (random)) 1))

(define (monte-carlo trials experiment)
  (define (iter trials-remaining trials-passed)
    (cond ((= trials-remaining 0)
           (/ trials-passed trials))
          ((experiment)
           (iter (- trials-remaining 1) (+ trials-passed 1)))
          (t
           (iter (- trials-remaining 1) trials-passed))))
  (iter trials 0))