Suggested Solutions Here [Exam 2]

[anonymous12]

Your solutions are gay. Wheres Mao?

http://vcenotes.com/forum/index.php/topic,7394.0.html

Mine are there.

Thanks man.

[nathankb]

can someone please explain q1aiii? thanks:)

[flubbles]

can someone please explain q1aiii? thanks:)

What is the probability, correct to three decimal places, that her first 4 attempts at scoring a goal are successful, given that exactly 6 of her first 8 attempts at scoring a goal in a match are successful?

Combinatorics solution:

• Given exactly 6 successes == given exactly 2 failures
• Our probability space has these 2 failures anywhere in the 8 attempts, so 8 choices for the first fail * 7 choices for the second fail = 56
• The event we want has these 2 failures anywhere in the last 4 attempts, so 4 choices for the first fail * 3 choices for the second fail = 12
• 
  

[Synesthetic]

^ Yup that's right, or if you like:

She shoots for goal 8 times;

Split the problem into two scenarios: the first four shots at goal[1], then the next four[2].

[1] Probability she scores each of the first four times
n=4, r=4, p=0.8 => Pr(X=4) = (4C4)(0.^4(0.2)^0 = 0.8^4 = 0.4096

[2] Probability she scores two of the next four times
n=4, r=2, p=0.8 => Pr(X=2) = (4C2)(0.^2(0.2)^2 = 0.1536

[1] x [2] = 0.063 to 3 d.p.

From part a)ii) of that question, Pr(X=6) = 0.2936

Conditional probability: 0.063 / 0.2936 = 0.214 to 3 d.p.

[Synesthetic]

ii) 1/e

are you sure? i have 1/(e^7)

1/e is correct

3g should have + 16 instead of 8 shouldnt it

No, curve CD is 8 units above curve AD. Although each time he takes a capsule z increases by 16, each day z decreases by 8; there is a net gain of 8 z-units.

[pg88]

aarrrgh i hate conseqential marks! i screwed up that gradient (by not simplifying it properly) and i consequently lost about 10 marks!

fk =.= i did the same thing as u D= *hi5* lets go have our own party

[rustic_metal]

where is the answer to Q1)cii)

c)i) Negative quasi-parabolic curve over [2,6] (somewhat skewed to the right), maximum turning point at (4.31,0.38)
(Best to draw a line along the x-axis to represent the '0 elsewhere')
ii) 0.1211

3)a) 191 minutes; t~3.19 hours = 191.67 days = 192 minutes after rounding, BUT at 192 minutes he is DEAD, therefore 191 minutes is correct

It specifically asks you to round to the nearest minute, therefore even if it was 191.5001 you'd round to 192, not 191.

It's like if they had asked you to round to the nearest integer of, say, rabbits, when you find there are 1.6 rabbits. Even though, normally, you'd round down, here you must round to 2.

The question asks for the "time...[he] has to find an antidote"

If you state 192 minutes, he doesn't HAVE that amount of time, he'll be dead by then.

Thus you round down to 191 minutes.

Yes, but to refer again to the rabbits example; even if you do not have 2 rabbits, you'd round to whatever they ask you.

Its a debate of semantics I suppose. Meh, not gonna bother continuing this then.

Yeah, I agree. I was furiously debating with myself whether to change it or not as the examiner came up the row to collect my paper

Yes, I was too. I ended up deciding on 191, because it takes the reality of the scenario into account. If the question had asked "Rounded to the nearest minute, how long until the concentration is 100" perhaps 192 would have been better, but it specifically asks how long he has to get the antidote before he dies. I hope VCAA see it our way.

They may accept both - depending on the way you structured your argument. They should allow some leeway given the ambiguity of the question stem...

'to the nearest minute' would imply that it has to be an integer value of minutes. He is dead by the end of that minute, so he doesnt have that minute to find an antidote. That phrase just stops people from putting decimal answers.

[Synesthetic]

where is the answer to Q1)cii)

c)i) Negative quasi-parabolic curve over [2,6] (somewhat skewed to the right), maximum turning point at (4.31,0.38)
(Best to draw a line along the x-axis to represent the '0 elsewhere')
ii) 0.1211

3)a) 191 minutes; t~3.19 hours = 191.67 days = 192 minutes after rounding, BUT at 192 minutes he is DEAD, therefore 191 minutes is correct

It specifically asks you to round to the nearest minute, therefore even if it was 191.5001 you'd round to 192, not 191.

It's like if they had asked you to round to the nearest integer of, say, rabbits, when you find there are 1.6 rabbits. Even though, normally, you'd round down, here you must round to 2.

The question asks for the "time...[he] has to find an antidote"

If you state 192 minutes, he doesn't HAVE that amount of time, he'll be dead by then.

Thus you round down to 191 minutes.

Yes, but to refer again to the rabbits example; even if you do not have 2 rabbits, you'd round to whatever they ask you.

Its a debate of semantics I suppose. Meh, not gonna bother continuing this then.

Yeah, I agree. I was furiously debating with myself whether to change it or not as the examiner came up the row to collect my paper

Yes, I was too. I ended up deciding on 191, because it takes the reality of the scenario into account. If the question had asked "Rounded to the nearest minute, how long until the concentration is 100" perhaps 192 would have been better, but it specifically asks how long he has to get the antidote before he dies. I hope VCAA see it our way.

They may accept both - depending on the way you structured your argument. They should allow some leeway given the ambiguity of the question stem...

'to the nearest minute' would imply that it has to be an integer value of minutes. He is dead by the end of that minute, so he doesnt have that minute to find an antidote. That phrase just stops people from putting decimal answers.

Yup, that was my answer.

Although in the 2002 paper exam 2 final question - an 'adventure park ride' first reaches 24 metres above ground level at 55.32 seconds, but in their solutions VCAA gave 55 seconds - even though 'logically' the ride hasn't reached 24 metres high yet.

But today's question was somewhat different, someone's life was at stake

[Pandemonium]

no it wasn't he lived anyway.

[mskwmskw]

wht are the CAS solutions???

[/0]

where is the answer to Q1)cii)

c)i) Negative quasi-parabolic curve over [2,6] (somewhat skewed to the right), maximum turning point at (4.31,0.38)
(Best to draw a line along the x-axis to represent the '0 elsewhere')
ii) 0.1211

3)a) 191 minutes; t~3.19 hours = 191.67 days = 192 minutes after rounding, BUT at 192 minutes he is DEAD, therefore 191 minutes is correct

It specifically asks you to round to the nearest minute, therefore even if it was 191.5001 you'd round to 192, not 191.

It's like if they had asked you to round to the nearest integer of, say, rabbits, when you find there are 1.6 rabbits. Even though, normally, you'd round down, here you must round to 2.

The question asks for the "time...[he] has to find an antidote"

If you state 192 minutes, he doesn't HAVE that amount of time, he'll be dead by then.

Thus you round down to 191 minutes.

Yes, but to refer again to the rabbits example; even if you do not have 2 rabbits, you'd round to whatever they ask you.

Its a debate of semantics I suppose. Meh, not gonna bother continuing this then.

Yeah, I agree. I was furiously debating with myself whether to change it or not as the examiner came up the row to collect my paper

Yes, I was too. I ended up deciding on 191, because it takes the reality of the scenario into account. If the question had asked "Rounded to the nearest minute, how long until the concentration is 100" perhaps 192 would have been better, but it specifically asks how long he has to get the antidote before he dies. I hope VCAA see it our way.

They may accept both - depending on the way you structured your argument. They should allow some leeway given the ambiguity of the question stem...

'to the nearest minute' would imply that it has to be an integer value of minutes. He is dead by the end of that minute, so he doesnt have that minute to find an antidote. That phrase just stops people from putting decimal answers.

Yup, that was my answer.

Although in the 2002 paper exam 2 final question - an 'adventure park ride' first reaches 24 metres above ground level at 55.32 seconds, but in their solutions VCAA gave 55 seconds - even though 'logically' the ride hasn't reached 24 metres high yet.

But today's question was somewhat different, someone's life was at stake

It's Tasmania Jones; no matter what, he must survive until the 2009 Methods exams.

[JackOfSpades]

for the question about finding an equation for CD i think it was... you've got 16/d+8 which works but so does 48/(d+1) are these equivalent??? am i missing something.... because if you sub in 1 and 2 you get 24 and 16 respectively and for yours it is the same...

[/0]

for the question about finding an equation for CD i think it was... you've got 16/d+8 which works but so does 48/(d+1) are these equivalent??? am i missing something.... because if you sub in 1 and 2 you get 24 and 16 respectively and for yours it is the same...

They say that the shape of CD the same as the shape of AB, so I assume you can only use translations, not dilations to find CD.

[sailavan]

LOL, THIS POO WAS SO FRCKIN' EASY.
FINISHED WITH 30 MINUTES TO GO.

But still, I still got that gosh darned poo-faced fucker 1c (or was it d) wrong.

GAHHH DAMN!

[Charbel]

Atm i stand at 100% on both exams. I actually thought i was wrong about the "6 days" question... Because everyone told me i was.. Maybe i wasn't?