裁判員になる確率は1/100です - www.textfile.org
883840239413745673888484367614071057790536685391943120866342686853088554088962741529800523812714432924482598710613913144352575140063676571506082961578643064214433481064949969375249999 / 88817841970012523233890533447265625000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
で約 0.00995115643219699 ですかね。
Ruby 先生に解いてもらいました。
def f(rat, times) d = rat.denominator n = rat.numerator result = n (1...times).each do |i| result = n * d ** i + (d - n) * result end result.quo(d ** times) end puts f(1.quo(5000), 50)
短く。
n, d, times = 1, 5000, 50 puts times.times.inject(0) {|r, i| n * d ** i + (d - n) * r }.quo(d ** times)