Computational goodies and stressful everyday

( Computer crisis resolution... )

( ...and the stress )

These here probablities - dem are damn hard things, ya'know.

Just sitting around correcting a maths competition for mathematics teachers; when I run across a guy who seriously does this funky trick:

Question: Given that a sequence of cointosses has produce a Head - what's the probability that the next toss is a Head as well?
Answer: The probability for a 1 long streak of heads after this first is 25% (HT)
The probability for a 2-streak is 12.5% (HHT)
The probability for a 3-streak is 6.75% (HHHT)

Summing up this is the sum from 1 to oo of 1/2^n. This sum converges to 1/2. Thus P(H)=0.5