ST6 Sept 2013 Q1

Discussion in 'SP6' started by trog_8, Jan 4, 2023.

  1. trog_8

    trog_8 Made first post

    Hi all,

    I am getting myself confused with the lognormal distribution in this question and I was hoping someone would be able to help me.

    I can understand why Ln(S4) follows a N(-15.697,50) distribution.

    Now my current understanding is that S4 should then follow a LogNormal distribution with mean exp(mu + 0.5*sigma^2) and variance exp(2*mu +sigma^2)*(exp(sigma^2) - 1) where mu and sigma^2 are the mean and variance of Ln(S4) respectively.

    However, the examiners report has S4 as having a mean of -15.697 and variance 50 which is equal to mu and sigma.

    Following my understanding/method I get a S4 mean of 10,971.

    Thanks
     

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