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Wait sorry why does this argument fail? There are only two possible cases: Ben flips more heads than Amy or Ben flips more tails than Amy, and the 2nd case obviously includes the circumstances where Ben gets the same amount of heads as Amy, as he would have to have more tails then. Then since...

Yeah I didn't think it was gonna be 1/2 initially either. I ended up coming up with that evil binomial theorem solution,which resulted in 1/2, and then figured out why it worked from there. Now I have wasted my Tuesday night lol.

Yeah I believe it only works for n, (n+1). Because if you take, for example n, (n+2), then it is possible for Ben to have more tails and more heads that Amy, adding a complete new case. Since there are more cases to consider here than just having more heads or more tails, the probability will...

There are two cases to consider: Ben obtains more tails than Amy, or Ben obtains more heads than Amy. Since it is a fair coin, these two cases have the same probability, by symmetry. That means that the probability that Ben obtains more heads is exactly a half. This can also be proven using...

Is the answer 1/2? You can tell by symmetry, but it can be proven using binomial probability and binomial theorem as well.

Lol nice, I didn't know it went that deep. Highest I've ever gotten on it was high distinction in year 8 or something, and have only ever gotten credits/distinctions since then. I'm angry about the one this year though, the website kept crashing for us and there were like at least 3 of the last...

Yeah I feel that, English is shit. My teacher got me to have a brief look at linear algebra and taylor series/convergence tests, as well as 1st and 2nd order differential equations, just from a textbook. How do the comp streams work though? Our school kinda just called a few of us in to do the...

Nice, my school barely let me accelerate advanced in year 11 lol. My maths teacher had to argue with the principal for ages. We don't have an Australian maths competition stream or anything though, and I hate doing those comps anyway because I suck at them lol. Still super impressive result for...

My Attempt:

Surely it can't be this simple?

Damn that sucks. Hopefully this year the top 10 don't all get 100 again, because I guarantee I will make at least 1 stupid arithmetic error or some other dumb mistake. Btw I noticed that you did extension 2 in 2017 but are doing your other subjects this year, did you accelerate extension 2 in...

Do you know if any big selective/private schools that write their own papers (Ruse, Baulko, Grammar etc) have received their trial papers back yet?

Damn only losing two marks is quite impressive, even in an easier paper. I always lose a few to ridiculously stupid mistakes - in my trial I did stuff like drawing a force diagram wrong and forgetting to square root for the modulus of a complex number, which stopped me from getting 100. If the...

Yeah it sucks that these companies have such strict copyright laws, and I agree it would be beneficial to our hsc to have access to these papers, but it isn't worth the risk. All we can hope now is that people who go to schools that write their own trial papers will upload them. I just wish more...

Nice lol. Do you by any chance know what mark they got raw?

Interesting. Are you the person who topped the state in 2006 by any chance lol?

The last question of 2014 is quite easy, I agree, but I found part ii of the circle geo problem to be a bit tricky, but once you see the angle of revolution it is quite simple. Also question 10 is a joke compared to that of other papers. Still, I would put it as harder than 2017 and 2006...

Yeah I still think the easiest hsc year for extension 2 was 2006, but that might be because 2017 was literally one of the first past papers I ever tried doing for X2, and I wasn't as confident with circular motion yet, so that question did throw me a bit, but I see it is pretty generic now...

Yeah I guess. I heard about the top last year only getting like 98 raw, which is why I thought the comment about 99 raw not being a state rank at all was a little off

Yeah that seems accurate, but the only year I've heard of it happening was 1993. 2017 was an easier year IIRC, so all the top 10 getting 100 raw seems sort of plausible I guess.