Total weight of (36 + 44) Students, = (36 × 40 + 44 × 35) kg = 2980 kg Therefore average weight of the whole class, = 2980/80 = 37.25kg. Therefore average weight = 37.25 kg.
According to the question, Average of 25 observations = 13 Sum of 25 observations = 13 × 25 = 325 One observation entered wrongly 48 instead of 73. ∴ Difference = 73 – 48 = 25 (less) ∴ Actual sum of 25 observation = 325 + 25 = 350 Actual average = 550/25