[Lign251] Regarding question 3 on HW2

[Roger Levy]

Rebecca Colavin wrote:

> On Sun, 14 Oct 2007, Roger Levy wrote:
> 
>> Hi Alex (and everyone),
>> 
>> Alex Del Giudice wrote:
>>> I'm having a bit of trouble with question 3.  I think I have a 
>>> solution IF I assume that k is the number of failures, but this 
>>> isn't specified in the question.
>> Yes, this is right -- k is the number of failures.  Apologies for 
>> not specifying this more clearly!
> 
> Woah. I thought k was the number of flips. So the number of flips 
> must be equal or higher than the number of successes otherwise how 
> can k be a member of the set {r, r+1, r+2...}. Number of failures
> should be k-r?. The number of failures could be less than the number
> of successes, surely?
> 
> Sorry to be dense.

Ack -- you are right.  This is what I get for answering questions about 
homework before breakfast.

k is the number of *total flips* in a trial.  Number of failures is k-r. 
  Thank you for catching my mistake, Rebecca.

Roger