The Student Room Group
Reply 1
anyone :tongue:
Reply 2
The moment generating function of X ~ N(u, p2) is MX(t) = exp(tu+t2p2/2). So if we define a new random variable Y = aX+b, we have

MY(t) = E(et(aX+b)) = etbMX(ta) = exp(t(au+b) + t2(ap)2/2)

And now by comparison with MX(t), the moment generating function for a standard N(u,p2) variable, we see that Y ~ N(au+b, a2p2).

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