func generate_statistics(n) {
    var(sum=0, sum2=0)
    var hist = 10.of(0)
 
    n.times {
        var r = 1.rand
        sum += r
        sum2 += r**2
        hist[10*r] += 1
    }
 
    var mean = sum/n
    var stddev = sqrt(sum2/n - mean**2)
 
    say "size: #{n}"
    say "mean:   #{mean}"
    say "stddev: #{stddev}"
 
    var max = hist.max
    for i in ^hist {
        printf("%.1f:%s\n", 0.1*i, "=" * 70*hist[i]/max)
    }
    print "\n"
}
 
[100, 1000, 10000].each {|n| generate_statistics(n) }