General

Firstly, P = { H-H, H-T, T-H, T-T }. Since there's a guarantee of "at least one head", T-T is impossible. ---> P = { H-H, H-T, T-H }. We don't know if it will be the 1st or 2nd coin which has the guarantee (I [i]guess[/i]... there's a matter). Therefore, we can NOT do it with only 1 coin. In this situation, it's [b]false[/b] when P = { H-H, H-T } or P = { H-H, T-H }. The probability is still P = { H-H, H-T, T-H } ---> so H-H = 1/3 = 33.33 % = ~ 33 %. I suppose that's 33%. Otherwise, I [i]doubt[/i] it should be 50% if my answer is inexact.

Hm... Since both sides are tails, 0%. Trick question, good job ness.

[quote=LowWillpower]Sure they do, this just isn't the same as -4^2.[/quote]

It's -16 and anyone who says otherwise is an artsie.

50% times 100%?
So 50%?

Since they're independent events, it's a half chance of getting heads on the first one, and the second one is 100% chance because you said you have to get heads once.
Multiply those two since you're thinking of both of them as one event, and you get 50%?

all i know that the event of that probability is independent
I'm in stats and not doing too hot at all..

@LowWillpower:

Ooo ambiguous math problems. Very funny how worked up people get over being right about them.

Part of me wants to see a thread like that pop up just to see how fast an argument will start

[quote=UglierBetty]Y'know I kind of miss the flame war that would have erupted in this thread a few years ago, haha

but then again it's nice to see people on here don't get riled up so easily as they used to[/quote]
Sure they do, this just isn't the same as -4^2.

Y'know I kind of miss the flame war that would have erupted in this thread a few years ago, haha

but then again it's nice to see people on here don't get riled up so easily as they used to

I got 50% the first time I did this, but the second time I got 75%.

It's a 50% chance.

It's 33%. Heads-Heads, Heads-Tails, and Tails-Heads all work while Tails-Tails does not, so you have a 1 in 3 chance.

heads-tails
heads heads
tails-heads
tails-tails
those are all the combinations you can get...so, I guess 25 percent

[quote=Skyenets]If you are guaranteed at least one head, there's a 50% chance that you get a second one. You don't take the first flip into account because you will get heads. In the second flip you have 50% chance of getting tails and 50% chance of getting heads. Thus it being 50% chance of getting heads twice.

EDIT: Basically it's like asking what the chances are if you were only flipping one coin and asking what the chances are of getting one of the sides. I'm pretty sure the explanation is right. I might be off on the percentages. I don't know why, I'm starting to doubt myself and think that it might be 75%. No idea why.[/quote]

He said "guaranteed at least one head" but doesn't state whether it is in 1st coin or 2nd coin. I took it as both, and only moment when both coins aren't head is getting tail twice, which then ruled out leaving three possible outcomes: HH, HT and TH.

In your case however, if it says [i]given 1st coin is head[/i] then yes it's 50% chance and you would be correct.

EDIT: Forgot to add that assuming two coins are flipped simultaneously; TS did not state that he is flipping a coin twice.

33%, 50%, or 75%. It varies because there really isn't enough information. Is this your homework?

0.25 I believe.

P ( 2H / H )

=

P ( 2H and H ) / H
( 0.25 x 0.5 ) / 0.5 = 0.25

Could be wrong though I'm on holiday and my stats is pretty rusty I know this is the formula for when something is given though.

If you are guaranteed at least one head, there's a 50% chance that you get a second one. You don't take the first flip into account because you will get heads. In the second flip you have 50% chance of getting tails and 50% chance of getting heads. Thus it being 50% chance of getting heads twice.

EDIT: Basically it's like asking what the chances are if you were only flipping one coin and asking what the chances are of getting one of the sides. I'm pretty sure the explanation is right. I might be off on the percentages. I don't know why, I'm starting to doubt myself and think that it might be 75%. No idea why.

Clearly 100%

I would say 66 percent!

It's 33%. If you're given a head and the flips are independent there's no way you can get a TT leaving the possible
outcomes at a HH, TH, HT. (1/3) Im pretty sure there was a more strict formula for problems like this but I havent come across proability in forever so I forgot everything.

At least one head:

Possible outcome: HH, HT, TH.

Chance of getting HH = 1/3

Possible combinations:
Head 1st Tail 2nd
Tail 1st Head 2nd
Head 1st Head 2nd

so...I guess it's 33.33% chance?

Stats is boring, the answer is the probability of one heads then tails plus the reverse plus two heads. I don't feel like solving the problem though.

I'm probably over-analyzing it but I want to say 0 percent.

Heads-Head
Heads-Tails
Tails-Tails
Tails-Heads

25% probably, cuz u didnt specify what kind of head...

Lol, it's 33%.. Right? o-o..

[url=http://www.youtube.com/watch?v=pME-40poloQ]http://www.youtube.com/watch?v=pME-40poloQ[/url]

C'mon guys, no one has gotten it right.

Yeah you can ignore the guaranteed one since they are two separate events. I'm goin with 50%

Is this your homework.

There's only 3 possible combinations of coins: tails-tails, heads-tails, and heads-heads. So without the guaranteed head it's 33% and with the guaranteed head it is 50%.

[quote=HastyHeist]So you learned this in class and felt the need to share it because you were one of the derps that got this wrong, correct?[/quote]

No, it's just fun to post stuff like this on the forums. I took stats 5 years ago.

So you learned this in class and felt the need to share it because you were one of the derps that got this wrong, correct?

Fifty percent?