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Task/Statistics-Basic/Racket/statistics-basic.rkt

@@ -0,0 +1,21 @@
+#lang racket
+(require math (only-in srfi/27 random-real))
+
+(define (histogram n xs Δx)
+  (define (r x) (~r x #:precision 1 #:min-width 3))
+  (define (len count) (exact-floor (/ (* count 200) n)))
+  (for ([b (bin-samples (range 0 1 Δx) <= xs)])
+    (displayln (~a (r (sample-bin-min b)) "-" (r (sample-bin-max b)) ": "
+                   (make-string (len (length (sample-bin-values b))) #\*)))))
+
+(define (task n)
+  (define xs (for/list ([_ n]) (random-real)))
+  (displayln (~a "Number of samples: " n))
+  (displayln (~a "Mean: " (mean xs)))
+  (displayln (~a "Standard deviance: " (stddev xs)))
+  (histogram n xs 0.1)
+  (newline))
+
+(task 100)
+(task 1000)
+(task 10000)