Carrotsticks' Solutions 2015 Extension 1 HSC (2 Viewers)

[Bozzin8R]

Just wanna thank you for making my day by confirming I'll get an e4<333 85 HSC mark was my goal all year, but 59/70 should equate to well over 90 shouldn't it?

 

[asdfghjklqwerty]

would i get a carry on error if i got +30 instead of -30 for the angle in the projectile and so i said the particle was going up cos thats what my previous part gave me?

 

[Carrotsticks]

if I got 59/70 not counting any 'pity' marks is that a band 5?


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Just wanna thank you for making my day by confirming I'll get an e4<333 85 HSC mark was my goal all year, but 59/70 should equate to well over 90 shouldn't it?

I think 59/70 is low E4.

 

[TQuadded]

if I got 59/70 not counting any 'pity' marks is that a band 5?


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Pretty sure that's a low Band 6.

 

[Carrotsticks]

would i get a carry on error if i got +30 instead of -30 for the angle in the projectile and so i said the particle was going up cos thats what my previous part gave me?

I think if you got alpha = 30, and justified that since alpha is positive then ydot>0 etc etc, then you would've gotten a CFP (carry from previous).

In other words I think you would've still gotten the mark for part (iii), but I cannot be 100% certain of course!

 

[tondog]

is it ok to just get pi/6 for the the projectile? I proved that time is after max height in (iii) hence it is down but I used y/x in part ii and still got the same magnitude so would I still get the marks?

 

[tryhard1232]

If the q is a 1 marker and u make a silly mistake? will they give u the mark or not?

 

[Carrotsticks]

is it ok to just get pi/6 for the the projectile? I proved that time is after max height in (iii) hence it is down but I used y/x in part ii and still got the same magnitude so would I still get the marks?

You would have gotten the mark for both (ii) and (iii).

The question is asking for the angle that it makes with the horizontal. They didn't specify an orientation for the angle, so pi/6 is a valid answer.

There are 2 marks to the question. 1 mark would have been for finding ydot and xdot, the other mark would have been to make use of the formula tan(alpha)=blah to get the answer.

Unlikely they would dock you for having only pi/6 and not pi/6. By doing so, they are categorising you as a student who does not identify the tan(alpha) formula, which is most certainly not the case here.

 

[Carrotsticks]

If the q is a 1 marker and u make a silly mistake? will they give u the mark or not?

Depends on the type of silly mistake (transcription error? carry from previous? etc) and where the question is located in the paper.

 

[tryhard1232]

Depends on the type of silly mistake (transcription error? carry from previous? etc) and where the question is located in the paper.

hmmm it's question 14 c i) I wrote 6C4 x (1/2)^6 *(1/2) BUT after i walked out because i was rushing i was thinking i may have wrote the multiply sign as a + sign instead.

 

[Carrotsticks]

hmmm it's question 14 c i) I wrote 6C4 x (1/2)^6 *(1/2) BUT after i walked out because i was rushing i was thinking i may have wrote the multiply sign as a + sign instead.

Transcription error, you would've gotten the mark still. It is clear that you intended the multiply symbol.

 

[Drsoccerball]

For the projectile, since they didn't specify the orientation, is an angle of 150 degrees correct?

I guess...

 

[Carrotsticks]

For the projectile, since they didn't specify the orientation, is an angle of 150 degrees correct?

No, that is not correct because it means that the particle is flying backwards!

 

[tondog]

hmm, but i just used y/x not ydot/xdot and got the answer pi/6 lol, so I prob lose 1 mark? or would they be nice and only consider the magnitude of the answer in ii as direction is in iii

 

[ENFP]

I'm currently debating with someone as to whether Q1 was A or D. They think it's D because they gave x^3 -6x and not P(x)=x^3 -6x=0. That makes 0 sense to me, and I'm certain it was A because of Remainder theorem. To englishify my gibberish, he thinks that the remainder theorem doesn't apply to this question because they didn't equate it to 0 or something.... Any takers?

 

[expelliarmus]

if i put the angle in degrees for projecitle would i lose a mark? also what would 67/70 scale/alingn to?

 

[Drsoccerball]

I'm currently debating with someone as to whether Q1 was A or D. They think it's D because they gave x^3 -6x and not P(x)=x^3 -6x=0. That makes 0 sense to me, and I'm certain it was A because of Remainder theorem. To englishify my gibberish, he thinks that the remainder theorem doesn't apply to this question because they didn't equate it to 0 or something.... Any takers?

The question asked to find the remained no the quotient when it was divided by -3...

 

[Carrotsticks]

hmm, but i just used y/x not ydot/xdot and got the answer pi/6 lol, so I prob lose 1 mark? or would they be nice and only consider the magnitude of the answer in ii as direction is in iii

Oh right I see, I didn't see that you excluded the dots.

You would've lost a mark for part (ii) then. However, your argument for part (iii) is still valid.

I'm currently debating with someone as to whether Q1 was A or D. They think it's D because they gave x^3 -6x and not P(x)=x^3 -6x=0. That makes 0 sense to me, and I'm certain it was A because of Remainder theorem. To englishify my gibberish, he thinks that the remainder theorem doesn't apply to this question because they didn't equate it to 0 or something.... Any takers?

The remainder is ALWAYS at most one degree less than the dividend (which is linear in this case). That means the remainder MUST be a constant.

If your friend thinks that (D) is the answer, they probably found the quotient instead, not the remainder.

As for the remainder theorem not applying simply because they didn't define P(x) = blah... that's just silly.

 

[Carrotsticks]

if i put the angle in degrees for projecitle would i lose a mark? also what would 67/70 scale/alingn to?

No, you would have not lost a mark. Most likely that will align to 98 or 99.

 

[ENFP]

for 14ci, im not sure how but I ended up proving what they wanted via 7c5-6c5=6c4... will i get the mark with that?