april 2017 question 5.2

[dushyant kochar]

5 (i) -Show that the following discrete distribution { Bin(n,p) } belongs to the exponential family of distributions.

(ii) Derive expressions for the mean and variance of the distribution, E(y) and Var(y), using your answer to part (i).
[4 marks each]
in part 2 of the question what examiners are exactly looking for? do they want us to prove that
E(Y) =b'(Q) and var(Y) = a(o)b''(Q)
or they want us to use the result E(Y) =b'(Q) and var(Y) = a(o)b''(Q) and derive the mean and variance of y in terms of n and p ? plz help,

 

[John Lee]

It was unfortunate wording - as "derive" implies that we should derive the formulae (like we did in 2016) but the marks suggests otherwise. In this case it just meant quote and use the formulae.

 

[dushyant kochar]

Thank u sir

 

[dushyant kochar]

Sir the results came out and i cleared the paper. Thank u very much John sir for all your help , it mattered a lot