just starting and stuck already!

Discussion in 'CT5' started by Leila, Dec 18, 2007.

  1. Leila

    Leila Member

    Can anyone tell me why the answer to question 1.8 in the notes uses 0.95 to the power 25? I thought it would be nPx i.e. e-integral of 0.5 between 0 and 25.
     
  2. John Potter

    John Potter ActEd Tutor Staff Member

    Question 1.8

    Leila,

    Your idea would also work but you have confused q and mu. We are being told that q = 0.05 every year for the next 25 years. This is equivalent to a constant force of mortality of -ln (1-0.05) = 0.05129. If we integrate a constant over 25 years we get -ln (1-0.05) X 25. Taking your suggestion of doing e to the minus this, we get exp {-(-ln (1-0.05) X 25)} which is 0.95^25 as required. All round the houses though, orig solution is much nicer - to be employed after 25 years we need to not leave next year (prob 0.95) AND (times) not leave the year after (prob 0.95) AND (times) etc. etc. = 0.95 ^25

    Happy Xmas :)
    John
     
  3. Leila

    Leila Member

    Thank you John - I had a feeling I might be doing something silly!
    TV is so rubbish on Christmas day I was driven to study!
    Leila
     

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