4. A special 4-year endowment insurance is issued on (70). The death benefit schedule is as follows: year benefit 1 50 2 60 3 70 4+ 80 You are given: (i) Benefits are paid at the end of year. (ii) Mortality follows de Moivre's law with w = 120. (iii) i = 0. Calculate the variance of this insurance. 4. A special 4-year endowment insurance is issued on (70). The death benefit schedule is as follows: year benefit 1 50 2 60 3 70 4+ 80 You are given: (i) Benefits are paid at the end of year. (ii) Mortality follows de Moivre's law with w = 120. (iii) i = 0. Calculate the variance of this insurance