In article ,
wrote:

On Sat, 26 Feb 2005 09:15:41 -0800, Ron Garret
wrote:

Not only are you wrong, but you are clearly, demonstrably, and
self-evidently wrong. If you don't believe me, you can actually *do*
this experiment. Don't play the lottery or go flying until your engine
fails. Get a die. Pretend that rolling a six means your engine has
failed. Now ask yourself: are you more likely to roll a six if you roll
it once, or if you roll it 100 times? Clearly if you roll it once your
chances are one in six, and if you roll it 100 times the chances of
rolling AT LEAST ONE SIX in those hundred trials is very close to 1.
(0.99999998792532652 to be precise).


Let's look at this another way.

Let's say the probability of an engine failure is 1 every 10,000
hours.

Let's assume that I declare that I intend to fly 10,000 hours in my
lifetime. We would probably agree that my chances of an engine
failure in my lifetime approximates 1. A serious betting man would
not bet against my chances of having a failure.

Now let's say my life is half over, and I've flown 5000 hours without
having had my failure. (a perfectly acceptable supposition).

Now I am looking at the rest of my life, wherein I will fly the
additional 5000, hours. The probability of a failure is still 1 every
10,000 hours (nothing has changed with the equipment, etc., to change
the probability)

Therefore, now the chances of having an engine failure during the rest
of my life has DECREASED.

That's right. Just as if you get half-way through your hundred rolls of
the dice without rolling a six, your chances of rolling a six in your
remaining rolls are now less than they were when you started. In the
extreme, if you get through 99 rolls without rolling a six, your chances
of rolling a six on your last roll are just one in six. And if you get
through all 100 rolls without rolling a six your chances of rolling a
six from then on are zero, just as they would have been if you'd never
started rolling/flying to begin with.

Simply put, it's how much flying time you got in front of you, not
behind you, that determines your likelihood of experienceng a failure.

Obviously.

rg