SSC CPO SI and ASI Model Paper 5

(3) Sum of first seven numbers= 7 × 12 = 84
Sum of last seven numbers= 7 × 20 = 140
Average of 13 numbers = 12.4
Middle number = (84 + 140 – 13 ×12.4) [ ∵ Middle number = Sum offirst 7 numbers + sum of last 7numbers – sum of 13 numbers]
= 224 – 161.2= 62.8