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: \(B_3G_1\) 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 eyodwa yazo ingumfana owazalwa ngoLwesine. Yiqiniso, ngaphansi kokucabanga kwethu, zonke lezi zenzakalo zingenzeka ngokulinganayo. Kukhona \(27\) okungenzeka, okuthi \(14\) (lezo ezikumakholomu amabili okuqala) aqukethe intombazane. Ngakho-ke amathuba okuthi nginendodakazi \(14/27\approx 51,9\% \neq 50\%\) .