# Search results

1. ### CSSA 2019 Extension 2

Hello! I didnt do it, but how was it? Heard was a hard exam?
2. ### Modular arithmetic allowed in the HSC?

Are things such as modular arithmetic, which is SO COMMON, not allowed at all?
3. ### perms and combs

i am getting 4/2454, can someone check
4. ### Weird circle

GIving me aids. Please send help.
5. ### Differential equatuins new ext 1 sample questions what???

Can someone explain what is happening here, Im so lost. Hints would be liked more, rather do the question by myself. Im not doing it in 2020 but whatevs just bored rn
6. ### Combinatorics Gurus helpppp

For a poker hand (5 cards) what is the probability of getting a single pair I got: (13C1)(4C2)(48C3)/52C5 But the solution in cambridge says other wise. (13C1)(4C2)(12C3)4^3/52C5 I can understand where they are cming from But when i do 48C3 how am I over counting? This question is...
7. ### Last question hsc what is it gonna be

Anyway not a question or anything, and this already exists but im geussing seeing ext 2 and 2u exams were hard ext 1 might be a killer too. Oh god help me my ext 1 exam is next year with the final cohort to do with, arghhh, and 4u follows the year after, so new syllabus ummm, so last...
8. ### Yet another lovely perms and combs

Given 50 cards with the integers 1, 2, 3, ... 50 printed on them, how many ways are there to select 9 distinct cards, such that no two cards have consecutive numbers printed on them? I was told the answer is 42C9
9. ### Perms and Combs

Its the Gumtree Koala question from cambridge It says "If the letters of GUMTREE and the letters of the word KOALA are combined and arranged into a single 12 letter word how many arrangements have KOALA in the correct order" I got 11!/2! which is 19958400 Answer is 1995840 Its got one...
10. ### Perms and Combs

How many ways can you arrange COMBINATION so that the vowels are in alphabetical order and separated from each other by at least 1 consonant $Should'nt it be$ \frac{6!}{2!2!2!} \times 3 6! ways to arrange the consonants Repetitions: 2! of N 2! of I 2! of O and thre are...
11. ### Parametrics question

P is any variable point on the parabola x^2=-4y. THe tangent from P cuts the parabola x^2=4y at Q and R. Show that 3x^2=4y is the equation of the licus of the mid point of the chord RQ. PS: How do you activate LateX editor??
12. ### Circle Geo

its said a+b=c I went angle hunting but am repeating myself
13. ### Is this a bad habit?

I have read that Delta x on Delta y is different to dx/dy But im SOOO used to delta x/ delta y that when i do any questions i put it in. Is this technically wrong? or should i try to change this habit?
14. ### COmbinations

Nine persons gather to play football by forming two teams of four to play each other, the remaining person acting as referee.In how many different ways can the teams be formed? If two particular persons are not to be in the same team, how many ways are there then to choose the teams...
15. ### Combination

THis is from the 2015 perms thread A zoo keeper wants to place 6 tigers in 4 cages, each can fit a maximum of two tigers. In how many ways can he place the tigers if no cage to be left empty? I got 4! x (6C2 x 4C2 x 2C1 x 1C1) = 4320 Because: First Cage: 6C2...
16. ### Parametrics

Is it a good idea to memorise the results of the derivations, like Normals at points Cus i know the derivation itself is important but shouldnt memorising it be helpful later on? Keeping in mind i have never done parametrics or licus
17. ### Combination

Need help with this comb question Part i is fine but my answer of part ii isnt matching with the book,
18. ### Geometry Question

Well. this is the question: In a quadrilateral ABCD, a line AF parallel to BC meets BD in F and a line BE parallel to AD meets AC in E. Prove that EF is parallel to CD
19. ### Want to study in Universities like MIT or CalTech: Procedures and what to do

As the title sums it up, for someone who aspires to go to these top-notch unis, how they do it and the procedures behind it. I got some extracurricular activities, such as drawing (won competitions throughout school life) and playing piano and also am good in programming Im currently in Year 10...