Nginabantwana ababili, indodana eyazalwa ngoLwesine. Angakanani amathuba okuba ngibe nendodakazi? Ake sibonise izinsuku zesonto ngezinombolo \(1, 2, … , 7\) lapho \(1\ =\) uMsombuluko, \(2 =\) uLwesibili, njalo njalo. Manje singachaza umcimbi othi "Ngosuku \(n\) kwazalwa umfana" njengo \(B_n\) kanye nokufanayo ne- \(G_n\) .
Isibonelo, \(B_3\) isho umfana ozelwe ngoLwesithathu futhi \(G_1\) isho ukuthi intombazane izalwe ngoMsombuluko. Sisebenzisa lesi saziso singabhala izehlakalo ezifana nalezi: \(B_3G_1\) kusho: "Ingane yokuqala ingumfana owazalwa ngoLwesithathu kanti eyesibili intombazane ezelwe ngoMsombuluko".
Ake sicabange ukuthi amathuba okuthi umntwana azalwe nsuku zonke zesonto alingana (okungukuthi, njengobulili bomntwana, akulona iqiniso ngokuphelele, kodwa kuwukucabangela okunengqondo ukugcina inkinga ilula). Lokhu kuholela kulokhu okulandelayo \(27\) okungenzeka ngokufanayo ukuthi izingane zami ebezingazalwa ( \(B_4\) umele umfana owazalwa ngoLwesine):
$$
\begin{matrix}
B_4G_1 & G_1B_4 & B_1B_4 & B_4B_1\\
B_4G_2 & G_2B_4 & B_2B_4 & B_4B_2\\
B_4G_3 & G_3B_4 & B_3B_4 & B_4B_3\\
B_4G_4 & G_4B_4 & B_4B_4 & \\
B_4G_5 & G_5B_4 & B_5B_4 & B_4B_5\\
B_4G_6 & G_6B_4 & B_6B_4 & B_4B_6\\
B_4G_7 & G_7B_4 & B_7B_4 & B_4B_7
\end{matrix}
$$
Ithebula elingenhla liwuhlu oluphelele lwazo zonke izindlela izingane ezimbili ezingazalwa ngazo uma okungenani oyedwa wazo engumfana ozelwe ngoLwesine. Ngokwezinkolelo zethu, vele, zonke lezi zenzakalo zingenzeka ngokulinganayo. Kunezindlela ezingu \(27\) ezingenzeka, ezingu \(14\) kuzo (lezo ezisezinkombeni ezimbili zokuqala) zifaka phakathi intombazane. Ngakho-ke amathuba okuba ngibe nendodakazi angu \(14/27\approx 51,9\% \neq 50\%\) .