2015 csaa mathenatics paper (1 Viewer)

SlimiJay · Jul 30, 2015

post your answers here for questions you remember

Drsoccerball · Jul 30, 2015

Or post questions you couldn't do and ill try to sovle them

SlimiJay · Jul 30, 2015

hahah that would be better
1/75 probability to win a lottery. a patron can only enter once in a day. how many time must the draw lottery take place in order to have a 95% chance of wining

calledtobebold · Jul 30, 2015

(a) Show that (X-1)X(X+1) = X^3-X
(b) Now consider y=(x+198)(x+199)(x+200). Hence or otherwise find the y-value of the minimum turning point.

Drsoccerball · Jul 30, 2015

SlimiJay said:
hahah that would be better
1/75 probability to win a lottery. a patron can only enter once in a day. how many time must the draw lottery take place in order to have a 95% chance of wining

$(\frac{74}{75})^n=\frac{5}{100}$

$n=223.18$

$\therefore n=224$

SlimiJay · Jul 30, 2015

werent they y=(x+1999)(x+2000)(x+2001)??

SlimiJay · Jul 30, 2015

thank the lord got that one right thanks

calledtobebold · Jul 30, 2015

Yes they were, sorry!

Drsoccerball · Jul 30, 2015

calledtobebold said:
(a) Show that (X-1)X(X+1) = X^3-X
(b) Now consider y=(x+198)(x+199)(x+200). Hence or otherwise find the y-value of the minimum turning point.

a) $x^3-x=x(x^2-1)=x(x-1)(x+1)$
b) $Let B=199 or 2000 $ or whatever the middle value is $$
$((x+b)-1)(x+b)((x+b)+1) = (x+b)^3 -(x+b)$

$\frac{dy}{dx}= 3(x+b)^2-1$

continue...

Drsoccerball · Jul 30, 2015

I only able to answer a few more

SlimiJay · Jul 30, 2015

i expanded part b and then derived and solved for x is that wrong?

Drsoccerball · Jul 30, 2015

SlimiJay said:
i expanded part b and then derived and solved for x is that wrong?

It says hence or otherwise expanding would give you 9 terms i think

But you are allowed to do that not very elegant tho

SlimiJay · Jul 30, 2015

yeah it was ugly hahaha but think i got it right

Drsoccerball · Jul 30, 2015

SlimiJay said:
yeah it was ugly hahaha but think i got it right

They should've put hence to separate the bands...Anyways i have to study english laters

john1464 · Jul 30, 2015

For the probability one on the last page I did 0.95=(74/75)^n and got the wrong answer but can I still get a mark even though I didn't do the 1-? And sorry for not using latex I need to learn.

sharoooooo · Jul 30, 2015

Did anyone get the pyramid question? i think it was Q16c?
You had to prove theta

SlimiJay · Jul 30, 2015

https://www.facebook.com/photo.php?fbid=1635146766770326&set=p.1635146766770326&type=1&theater
i uploaded this earlier

sharoooooo · Jul 30, 2015

Omg was it not a pyramid

sharoooooo · Jul 30, 2015

I thought DB was connected... omg -_-

sharoooooo · Jul 30, 2015

thanks

2015 csaa mathenatics paper (1 Viewer)

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