Ndinabantwana ababini, unyana ozelwe ngoLwesine. Angakanani amathuba okuba ndibe nentombi? Masibonise imihla yeveki ngamanani \(1, 2, … , 7\) apho \(1\ =\) uMvulo, \(2 =\) uLwesibini, njalo njalo. Ngoku singachaza isiganeko esithi "Ngosuku \(n\) kwazalwa inkwenkwe" njengo \(B_n\) kwaye ngokufanayo ne \(G_n\) .
Umzekelo \(B_3\) ithetha inkwenkwe ezelwe ngoLwesithathu kwaye \(G_1\) ithetha ukuba intombazana izalwe ngoMvulo. Sisebenzisa olu bhalo singabhala iziganeko: \(B_3G_1\) ithetha: "Umntwana wokuqala yinkwenkwe ezelwe ngoLwesithathu kwaye umntwana wesibini yintombazana ezelwe ngoMvulo".
Makhe sicinge ukuba amathuba okuba umntwana azalwe yonke imihla yeveki alinganayo (okuthi, njengesini somntwana, asiyonyani ngokupheleleyo, kodwa yingcinga efanelekileyo yokugcina ingxaki ilula). Oku kukhokelela koku kulandelayo \(27\) ngokulinganayo iindlela abantwana bam abanokuba bazalwe ngayo ( \(B_4\) imele inkwenkwe ezelwe ngoLwesine):
$$
\begin{matrix}
B_4G_1 & G_1B_4 & B_1B_4 & B_4B_1\\
B_4G_2 & G_2B_4 & B_2B_4 & B_4B_2\\
B_4G_3 & G_3B_4 & B_3B_4 & B_4B_3\\
B_4G_4 & G_4B_4 & B_4B_4 & \\
B_4G_5 & G_5B_4 & B_5B_4 & B_4B_5\\
B_4G_6 & G_6B_4 & B_6B_4 & B_4B_6\\
B_4G_7 & G_7B_4 & B_7B_4 & B_4B_7
\end{matrix}
$$
Itheyibhile engentla luluhlu olupheleleyo lwazo zonke iindlela abantwana ababini abanokuzalwa ngayo ukuba omnye wabo yinkwenkwe ezelwe ngoLwesine. Ewe, phantsi kweengcinga zethu, zonke ezi ziganeko zinokwenzeka ngokulinganayo. Kukho \(27\) okunokwenzeka, apho \(14\) (ezo zikwiikholamu ezimbini zokuqala) zinentombazana. Ngoko ke amathuba okuba ndibe nentombi \(14/27\approx 51,9\% \neq 50\%\) .