# Maths Extension 2 predictions/thoughts? (1 Viewer)

Moderator

#### Idkwhattoput

##### Member
Turns out I somehow didn't see a 3 mark question. Rip. Now looking at high 80s. 97 still achievable?

#### Jimmy.Chen

##### New Member
Turns out I somehow didn't see a 3 mark question. Rip. Now looking at high 80s. 97 still achievable?
I think so. In 2013 88 got scaled to 97.

#### Trebla

How does one like probability
Tbf I don’t like perms/combs because I’m not the best at coming up with counting techniques but this question is not perms/combs.

The result in itself is nice using the golden ratio. Not to mention to get there it merges the concepts of probability, geometric series (if my solution to it is correct but there may be other approaches) and quadratic inequalities in the one question.

#### hash1234

##### New Member
would 70 just get me the b6 cut off? Super stressed atm

#### Drdusk

##### Moderator
Moderator
would 70 just get me the b6 cut off? Super stressed atm
It's cutting it pretty close. In 2018 a 72 Raw was 90 on the dot and this year seemed to be easier.

#### danny135

##### New Member
would 60 raw get me a band5???

#### Trebla

They went easy on the outgoing syllabus topics in this paper

#### Nash__

##### New Member
how long do we think for solutions??? tomorrow?

#### integral95

##### Well-Known Member
Tbf I don’t like perms/combs because I’m not the best at coming up with counting techniques but this question is not perms/combs.

The result in itself is nice using the golden ratio. Not to mention to get there it merges the concepts of probability, geometric series (if my solution to it is correct but there may be other approaches) and quadratic inequalities in the one question.
bruh I legit got it using only 2U knowledge why is this so easy?, but yeah the final result is indeed neat

#### psmao

##### Member
I like the probability question
Yeah I liked it but it was kinda repetitive to a 2u past hsc question 2015 iirc. U just need the limiting sum of the probability

#### teddyboy3

##### New Member
E4 cut off prediction?

#### aa180

##### Member
For the probability question, since player $\bg_white A$ starts first, player $\bg_white B's$ chance of winning is always dependent on player $\bg_white A$ failing the turn before player $\bg_white B$ selects a marble. This immediately forces the condition: $\bg_white \frac{w}{w+y} < \Big (\frac{y}{w+y}\Big )^{2} \Longrightarrow \frac{y}{w} - 1 - \frac{w}{y} > 0$. Let $\bg_white k = \frac{y}{w}$ and you quickly arrive at the inequality $\bg_white k^{2}-k-1> 0$, and the result follows.

#### tywebb

##### dangerman
Here are solutions jointly by fun_jirachi and ruiace:

#### Attachments

• 5.7 MB Views: 93

#### Idkwhattoput

##### Member
For the probability question, since player $\bg_white A$ starts first, player $\bg_white B's$ chance of winning is always dependent on player $\bg_white A$ failing the turn before player $\bg_white B$ selects a marble. This immediately forces the condition: $\bg_white \frac{w}{w+y} < \Big (\frac{y}{w+y}\Big )^{2} \Longrightarrow \frac{y}{w} - 1 - \frac{w}{y} > 0$. Let $\bg_white k = \frac{y}{w}$ and you quickly arrive at the inequality $\bg_white k^{2}-k-1> 0$, and the result follows.
The way I did it, was finding the probability that B wins, which is the sum of (A loses the B wins, A loses the B loses the A loses then B wins etc). Then you taking the limiting sum of this geometric series and set it greater then 1/2. The result follows.

#### worldno17

##### Active Member
do yall think they'll penalise in q13 projectile for using degrees? they didn't state anything about using radians

#### luckystrike826

##### New Member
what does everyone think a 90-93 will align to? thanks

#### 大きい男

##### Active Member
do yall think they'll penalise in q13 projectile for using degrees? they didn't state anything about using radians
If you are given the size of an angle in radians in the question I think it is assumed that your answer will be in radians. That said, asking for a decimal approximation of an angle isnt something that lends itself to be expressed in radians, so I think you would be unlucky to be penalised.