1. Department of Mathematics and Statistics, Hazara University Mansehra 23010, Pakistan
2. School of Statistics, Jiangxi University of Finance and Economics, Nanchang, P. R. China
3. School of Finance, Jiangxi University of Finance and Economics, Nanchang, P. R. China
4. Department of Commerce, Allama Iqbal Open University Islamabad, Islamabad, Pakistan