Unit for Business Mathematics and Informatics, North-West University, Potchefstroom Campus,
Potchefstroom, Republic of South Africa
Centre for Business Mathematics and Informatics, North-West University, Potchefstroom Campus,
Potchefstroom, Republic of South Africa
African Institute for Mathematical Sciences, Muizenberg, Cape Town, Republic of South Africa
Copyright © 2015 Masimba E. Sonono, Hopolang P. Mashele et al. This is
an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any
medium, provided the original work is properly cited.