9. A charitable organization decides to give old-age pension to people over sixty years of age. The scales of pension were fixed as follows: Age group Pension/ month(rs) 60-65 200 65-70 250 70-75 300 75-80 350 80-85 400 The age of 25 persons who secured the pension are as given below: 74 62 84 72 61 83 72 81 64 71 63 61 60 67 74 64 79 73 75 76 69 68 78 66 67 Calculate the monthly average pension payable per person and the standard deviation