Methods (CAS) 2009 exam 2 Suggested Solutions.

[hyperblade01]

With regards with 1e)i finding the rule

For f(g(x)) to exist , ran g needs to be a subset or equal to dom f right?

But dom f [0, infinity) whilst ran g is R?




EDIT: But I assumed it was possible otherwise that whole page woulda been blank

Range g is .

Idiot I am

Thanks

[hard]

ohkai.
how much would a ~15 out of 80 get me?

[NE2000]

Hey you say that you must STATE undefined. In the non-CAS one it was given that x does not equal zero. I just gave my answer as a hybrid for x>0 and x<0 without mentioning that it does not exist for x = 0 as that was given in the question. Do you think that's ok?

[almostatrap]

I checked the amended version, but I still think cii. is wrong unless I'm overlooking something which is very possible XD

You're told that you have a tin of balls, so can't you presume that X<68.5 and use 1 minus the result of ci as the probablity?

Thanks for the solutions by the way.

how else would they fit in the tin? lol

[jasrulz63]

PDF here

[GerrySly]

Hey you say that you must STATE undefined. In the non-CAS one it was given that x does not equal zero. I just gave my answer as a hybrid for x>0 and x<0 without mentioning that it does not exist for x = 0 as that was given in the question. Do you think that's ok?

I did exactly the same, but stating those restrictions you should be fine I reckon.

[TrueTears]

I checked the amended version, but I still think cii. is wrong unless I'm overlooking something which is very possible XD

You're told that you have a tin of balls, so can't you presume that X<68.5 and use 1 minus the result of ci as the probablity?

Thanks for the solutions by the way.

how else would they fit in the tin? lol

I'm pretty sure c ii) is right, just checked then with kamil.

[NE2000]

Yeah TT, for cii. You used 0.8385 for your value. But it says they picked up a tin of four balls at random. Each of the balls in that tin must fit in. So instead of using 0.8385 I think you should use the conditional probability given in ci which is 0.8985.

Let me explain a bit further:

A tin of four balls were selected. That means it is given that x<68.5, because any balls outside that range would not exist in a tin of four balls.
Now you need the probability that at least one is outside the range, which you have correctly identified to be 1 - the probability that all four are in the range. But the probability that all four are in the range must also take into account the fact that x < 68.5. Do you see what I'm saying? It's not the maths. It's the interpretation of the question :S

[Hooligan]

you're amazing TT.

[dcc]

If anyone's interested, question 3.g can be solved exactly.  The 'exact answer' can be found by solving the following equation for n.  

Anyone interested in the method can HIT ME UP in a pm.

[anti]

Yeah TT, for cii. You used 0.8385 for your value. But it says they picked up a tin of four balls at random. Each of the balls in that tin must fit in. So instead of using 0.8385 I think you should use the conditional probability given in ci which is 0.8985.

That's what I was thinking.  I originally had what TrueTears had but changed it later after some rereading.

[NE2000]

If I remember I think I got 0.3482 or something like that, anyone else recognize that?

[anti]

If I remember I think I got 0.3482 or something like that, anyone else recognize that?

Yep that's what I ended up getting as well (:

[StringFever]

Just putting it out there - to all those who are asking for non-CAS answers, there aren't many differences between TT's paper and the non-CAS paper.

Just ignore/note the differences in
MC - Q4, 5, 12, 18,
SA
- 1eii (they gave you a hint that x couldn't equal 0)
- 1eiii
- 2a (didn't need to solve for 3 simultaneous eqns; you were given the value of "a")
- MISSING FROM 2 - a question about the height of the mountain which was the same value as the depth of the valley
- 2d
- 3g

Apart from that, the questions are identical.

[angelboykevin]

just wondering if i get full mark for both exam1 and 2 and i get low or medium A+ for school sac, can i still get 50 studyscore??