1. Department of Mathematics, Pan African Insitute of Basic Science, Technology and Innovation, Nairobi, Kenya
2. Department of Statistics and Actuarial Sciences, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
3. Department of Accounting, College of Business Administration in Hawtat Bani Tamim, Prince Sattam bin Abdulaziz University, Hawtat Bani Tamim, Saudi Arabia
4. Department of Statistics and Operations Research, Faculty of Science, King Saud University, P. O. Box 2455, Riyadh 11451, Saudi Arabia
5. Mathematics Department, College of Science, Jouf University, P. O. Box 2014, Sakaka, Saudi Arabia
6. Department of Mathematics, Faculty of Science, Minia University, Minia 61519, Egypt