STEP exam question Statistics & probablility 2014-S2-Q13

GDC2022

Who can help to solve the STEP 2014 S2-Q13, the last question is a really problematic one.

Original post by GDC2022

Who can help to solve the STEP 2014 S2-Q13, the last question is a really problematic one.

Where have you got to? It's a multi-part question.

Edit: I'd say this is actually a fairly straightforward question - most of it is just applying definitions, and a little bit of logic about "what has to happen if X>=r and also if X=r?".

(edited 8 months ago)

Reply 2

GDC2022

Yes, the early part is easy.

Original post by DFranklin

Reply 3

mqb2766

Original post by GDC2022

Yes, the early part is easy.

ii) simply uses the definition of the expectation to write down a similar expression to i)
iii) uses the fact that if X>=k, there cant have been a repeat before k
iva) again the defn of the expectation operator and think about/rearrange how P(*=*) is related to P(*>=*)
ivb) uses/equates the results for ii) and iva)

It would help to see some working / attempt for a more specific hint.

Reply 4

DFranklin

Original post by GDC2022

Yes, the early part is easy.

To repeat myself: where have you got to?

As per the forum guidelines, if you want help you really need to post your working and explain where/why you're stuck.