“…Among the researchers who investigated the reliability and aging properties of the conditional random variable , , r k n t T , under various conditions and for different values of k and r , we can refer to Bairamov et al [1], Asadi and Bairamov [2,3], Asadi and Goliforushani [4], Li and Zhao [5] and Zhang and Yang [6]. The extension to coherent systems has also been considered by several authors; see, among others, Li and Zhang [7], Navarro et al [8], Zhang [9,10], Zhang and Li [11], Asadi and Kelkin Nama [12], and references therein.…”