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  1. B

    probability question

    another one:-@ (1) find the probability that in a family of four children 2 are boys and 2 are girls i got 3/8 (2) 2 women each have four children. what is the probability that neither woman has two boys and two girls 25/64?
  2. B

    series question

    thanks
  3. B

    series question

    -1<=x<=1 observe that: 1=1 2x=x+x 3x^2=x^2 + x^2 + x^2 4x^3=x^3 + x^3 + x^3 + x^3 by studying the above arrangements or otherwise find in simplest algebraic form an expression for the limiting sum of the series: 1 + 2x + 3x^2 + 4x^3 + ... + nx^[n -1]
  4. B

    probability question

    samantha has 3 similar keys in her pocket. to open her front door she tried the keys at random. she stopped trying when she opened the door and she did not use the same key twice find the probability that (1) the door opened when she tried the first key 2 she tried all three keys before the...
  5. B

    Trig help!!!!

    my bad....i swear when i type this on BOS I used ~ instead of =, yeah its approximations....
  6. B

    Trig help!!!!

    yeah thats what i did - my answer wasn't close enough
  7. B

    Trig help!!!!

    Show that (i) cos 46 (degrees) ~ [(root 2)/360)(180 - pi)] (ii) sin 29 (degrees) ~ (1/360)(180(root 3) - 1)) obv it has something to do with 45 + 1 = 46, and 30 - 1 = 29... i then tried using like...limx--> 0 cosx - 1/x = 1 and lim x-->0 sinx/x = 1....because u no - 1 degree is very close to...
  8. B

    Need help with trig/triangle question - HARD QUESTION!!!!!

    For part (ii) I got A= {[4(a^2)(c^2) - (b^2)(a+c)^2]/2} - is it correct? EDIT: is there an easier way to get the answer?? I did...Area of AOC = (b/2)(sin(theta))(a+c) cos(theta) = [b(a+c)/2ac]....then I drew a right angled triangle....hyptonuse = 2ac, adjacent = b(a+c), and opposite was...
  9. B

    Need help with trig/triangle question - HARD QUESTION!!!!!

    = D = D I got it! once you know the method it was suprisingly easy....but if someone didn't tell me to use areas I would never have been able to figure it out...
  10. B

    Need help with trig/triangle question - HARD QUESTION!!!!!

    (i) show that cos(theta) = [b(a+c)]/2ac (ii) if a=b and c=2b find the area of Triangle AOC No idea how to do part (i)...cosine rule?
  11. B

    Do people really give a crap about your Atar?

    no...just no... LOL, have u ever worked in your life shadowdude?
  12. B

    Does SC mean anything?! Compare your SC and HSC here.

    SC results: English - 88 Science - 98 Maths - 97 Geography - 94 History - 93 Computer crap - 95 HSC results: English Standard - 85 biology - 92 Chemistry - 87 3U maths - 95 4U maths - 92
  13. B

    HSC ATAR Drinking Game

    alcohol is bad for you kidz
  14. B

    HSC Mathematics Marathon

    Sorry guys someone please explain this to me, how do you know the series is geometric? havent done much work with series :S
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    Check my integration please:

    integrate [(x)/(1-x)]^0.5 using x= (sin theta)^2 My answer: inverse sine (sqrt(x)) - ((x)(1-x))^0.5 Wolfram is giving some retarded answer, please someone check for me
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    anyone who can do the paper in ~1hr and get 80+, I have a question for you!

    hmmm.... i've done papers where i've done q1-5 without taking a single break of thinkin, i.e. continuous writing nonstop yet it took me about 50 minutes - and i wrote fast...
  17. B

    2010 HSC Exam

    q6 (b) (iii, iv, v) and all of Q7 (c) were foookin hard - but i guess that was the only tricky parts
  18. B

    anyone who can do the paper in ~1hr and get 80+, I have a question for you!

    1-5 takes about 45-50 minutes. Q6 takes about 15 minutes. Q7 takes over 60-65 minutes. Basically I spend the whole fucking hour raking my brain trying to figure out how to finish Q7 LOL Btw how are you meant to use reading time? I normally scan thru the paper in the first 30seconds, and then...
  19. B

    2011 hsc mx1 marathon

    Woah.... proving statement for n = k+1 \textup{Prove for n = k+1}\\\\S_{k}\, +\: T_{k+1}\\\\\therefore \frac{(k+1)! - 1}{(k+1)!} \; \; \; + \; \; \; \frac{k+1}{(k+2)!}\\\\=\, \frac{(k+2)(k+1)! - (k+2)\: +\: (k+1)}{(k+2)!}\\\\=\frac{(k+2)! - 2 + 1}{(k+2)!}\\\\= \frac{(k+2)! - 1}{(k+2)!}\\\\=...
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