Discussion in 'Computer Support' started by Plato, Dec 13, 2004.

1. ### PlatoGuest

If I took a penny and flipped it 100 times and 99 times it came up Heads
what are the chances of it coming up Heads again on the 101st toss?

A: 50%
B: 75%
C: 99%

Plato, Dec 13, 2004

2. ### The Old SourdoughGuest

Plato gibbered the following deranged nonsense:
A:50%

The Old Sourdough, Dec 13, 2004

3. ### =?ISO-8859-1?Q?R=F4g=EAr?=Guest

Just now learning about statistics? It's always 50%, the penny can't
remember what it's done in the past.

=?ISO-8859-1?Q?R=F4g=EAr?=, Dec 13, 2004
4. ### Harvey GrattGuest

Only if the penny and the experiment aren't rigged. The real question
should be "what is the probability that the experiment is rigged given
the data?"

Harvey

Harvey Gratt, Dec 13, 2004
5. ### YddapGuest

In
99%

Yddap, Dec 13, 2004
6. ### Jock StrapGuest

A:50%. And no, it would never come up heads 99 times in a row either.
Yes, it's theoretically possible, but practically it wouldn't happen.

Jock Strap, Dec 13, 2004
7. ### Flying TigerGuest

Normally 50% cz lack off memory off penny,

if it came 99 times head up, i would check the other side off penny,

F.

Flying Tiger, Dec 13, 2004
8. ### PlatoGuest

False.

Plato, Dec 13, 2004
9. ### PlatoGuest

Correct. For a penny to come up Heads 99% of the time it has to be
rigged.

I imagine that you Harvey dont work in a cube but have an office with a
window

Plato, Dec 13, 2004
10. ### PlatoGuest

False.

Plato, Dec 13, 2004
11. ### PlatoGuest

False.

Plato, Dec 13, 2004
12. ### PlatoGuest

It came up once in Tails tho You can do the same with modified dice.

Plato, Dec 13, 2004
13. ### Jock StrapGuest

Which bit? The 50% or the 99 times? And both are true, anyway.

Jock Strap, Dec 13, 2004
14. ### PlatoGuest

Plato, Dec 13, 2004
15. ### ex cathedraGuest

If the coin is unbiased, it's 50-50, just like always.

However, the smart money here says the flipping is rigged since the chances
of 99 heads in a row in an unbiased coin is one out of two to the 99th
power...(you do the math)!

X

ex cathedra, Dec 13, 2004
16. ### Jim ScottGuest

Agreed. Coins have no memory.

Jim Scott, Dec 13, 2004
17. ### RichardGuest

Since you've ruled out 50% as your correct answer, which it should be, that
leaves two choices.
So the answer to YOUR question is 75% because 99% is impossible given the
conditions.

Technically though, the answer is correctly 50% because there are only 2
sides to the coin.

Besides, the vast majority of coins will undoubtedly land on the "tail" side
more times than not, due to the variance in the weight of each "side".

ya think he bought that one eh?

Richard, Dec 13, 2004
18. ### Trent SCGuest

If I took a penny and flipped it 100 times and 99 times it came up Heads
Yes, and don't confuse "mathematical probability" and "likely outcome". The
mathematical probability is 50%, as each event (a coin toss) is a unique
event in its own right, without influence from other events. As other
posters have said, the coin has no memory. It is statistically possible to
have a coin land on tails 99 times in a row. Lunatic and more unlikely than
my scoring tonight with Kylie, but still statistically possible.

However, if you look at the likely outcome, you are introducing
non-mathematical elements into the calculation. I personally wouldn't put
half the kid's college fees on tails, and I doubt if you would either, but
there you go.

Trent SC, Dec 13, 2004
19. ### anthonyberetGuest

None of them - it could land on its edge.
It would be very close to but lower than 50% assuming it was an
equally-balanced coin.
After 99 heads I would be tempted to check it wasn't a double header or a
trick coin in some way.
After all, what are the chances of throwing 99 heads in a row with an
even-chance coin?
(very, very low).

anthonyberet, Dec 13, 2004
20. ### anthonyberetGuest

It just depends how many times you throw it - a 99 run of heads is 100%
certain with an infinite number of throws.

anthonyberet, Dec 13, 2004