mind blowing!!!
for calculating E[Xi^3] Mgf came to my rescue but the way you solved E[ (ΣXi)^3 ] was simply awesome. Leave alone unbiasedness of estimators, I learnt so many things just by seeing the way u calculated E[Xi^3] and E[ (ΣXi)^3 ].
thank you so much. :)
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"You don't have to believe in God, but you should believe in The Book." -Paul Erdős