skyrockets1530
Member++
I tihnk it was 9pi or 20pi or something-cathie- said:
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jazzi_jess
20 days to go!
I agree it is in 2018, because it doesn't really matter if this is the 2017 or 2018 year or whatever, it only matters that AFTER THE END OF 12 years, there is still more to pay, which takes the last payment into the next year, 2018. I counted it on my fingers...
Anyway... I also agree that t=18mins 34secs and that was a good explanation, sorry, can't remember the name of the person who did it. I can't really remember the rest... and i've gotta stop procrastinating and do some study now
Anyway... I also agree that t=18mins 34secs and that was a good explanation, sorry, can't remember the name of the person who did it. I can't really remember the rest... and i've gotta stop procrastinating and do some study now
Pianpupodoel
Neurotic Member
A12 is 2016 isn't it?
Super confused now... I had down during the 13th year... but then changed it to the 12th (2017) ... But what i dont get is how there could be a small remainder to pay when they are equal annual repayments... Anybody wanna help me out and explain! Dont think i can think straight anymore! ... crazy test!jazzi_jess said:
i had a bit of trouble with 6bii as well. when u equated the derivative to 0 u ended up with t=60 cos theoretically that is the only SP cos all the waters drained. however if u graphed it it was a linear function and its minumum was at t=0 and -120L/min. the rate of decrease of the volume was therefore greatest when t=0 cos the initial rate was 120 L/min. i think i got it right but it took me a while to realise why working wiht the calc wasnt working. the graph never lies (un less u suck at drawing graphs)d3v1l_grl said:
Thanks
Hey thanks for that. Except with Q6 ai) I said "therefore the tank is DRAINING at a rate of 80L/min" I think that's the same as -80/L because the word draining implies that it is decreasing...or something like that...d3v1l_grl said:
orange_blob
Caveman
That's what I got, t=0.jebba_d said:
I find it hard to comprehend, though that the water is draining the fastest before any time has passed
I know this sounds rather stupid, but i find the easiest way is to count it out with your fingers.
A1 = End of 2005
A2 = End of 2006
A3 = End of 2007
A4 = End of 2008
A5 = End of 2009
A6 = End of 2010
A7 = End of 2011
A8 = End of 2012
A9 = End of 2013
A10 = End of 2014
A11 = End of 2015
A12 = End of 2016
Thus, since n was slightly greater than 12,
It follows that it would be repaid in 2017
I think that it would make more sense if it said "equal annual repayments of $480000 until An < $480000 when the remaining balance will be paid in full". Either that or everyone has screwed up the question completely!
What's done is done i guess...
A1 = End of 2005
A2 = End of 2006
A3 = End of 2007
A4 = End of 2008
A5 = End of 2009
A6 = End of 2010
A7 = End of 2011
A8 = End of 2012
A9 = End of 2013
A10 = End of 2014
A11 = End of 2015
A12 = End of 2016
Thus, since n was slightly greater than 12,
It follows that it would be repaid in 2017
I think that it would make more sense if it said "equal annual repayments of $480000 until An < $480000 when the remaining balance will be paid in full". Either that or everyone has screwed up the question completely!
What's done is done i guess...
Well, a similar question in the 2002 HSC which asked:nono said:
"at what rate was the water draining out when the cooler was one-quarter full?"
The answer in the back, which is from a book by the Mathematics Association of NSW, is provided at "The rate of draining at 5/12 L/s". So i figure if it's good enough for the Maths association, surely it's good enough for the BOS markers.
I did the same thing as you, purely because saying "draining at -80L/s" sounds contradictory.
Oso
Biotechnician in Training
-80L/s means that water is leaving rather than entering... at least that's my understanding.phil2005 said:
Can somebody explain for me q5 c)? I'm pretty sure it was finding the gradient then using the derivitive to find the point, but I dunno...
Hey guys just posting my answers, i realise a few ppl have put these down already but i guess it increases the probability of the ones put down being right... NO! no more probability! probability is over!! yes!!! so anyway...
For 10 part a) its all show that questions, the answers have already been posted.
For 10 part b) i) i got 7/16 _
For 10 part b) ii) i got t = 30 /2 (30 times the square root of 2).
really hopin those answers r right now, but who cares, its over.
with question 8c, part iii says in which year, everyone seems to b saying 2017, i took it as in what year, ie the 12th year of the investment. did anyone else do this? they'll probably mark that wrong or lose a mark or something wont they...
For 10 part a) its all show that questions, the answers have already been posted.
For 10 part b) i) i got 7/16 _
For 10 part b) ii) i got t = 30 /2 (30 times the square root of 2).
really hopin those answers r right now, but who cares, its over.
with question 8c, part iii says in which year, everyone seems to b saying 2017, i took it as in what year, ie the 12th year of the investment. did anyone else do this? they'll probably mark that wrong or lose a mark or something wont they...
Oso
Biotechnician in Training
Crap!! Yeah, I'm pretty sure that's right... I just screwed myself by not thinking and putting 1/300 * 1/299 * 1/298 Dammit!!
Oso said:
Yeah i agree with you that dV/dt = -80L/s DOES imply that it's leaving, however when putting it into a sentence I like "draining at 80L/s" because to me that makes more sense - the draining implies the negative nature of the rate.
As for 5c, here's the solution:
y = 2e^x + 3x
dy/dx = 2e^x + 3
Since gradient of y = 5x – 3 is 5 and it is gradient is parallel to this line:
2e^x + 3 = 5
2e^x = 2
e^x =1
Therefore x = 0
When x = 0, y = 2x1 + 0 = 2
Therefore P is (0,2)
but the question stated 'interest is calculated on the balance at the beginning of the year' and since n=12.2325phil2005 said:
therefore on the 13th year the final payment will be made...
therefore
2005 + 13 = 2018
therefore the council makes the final payment in 2018
Very close mate -Famine said:
P(One of each) = (100/300) * (100/299) * (100/298) * 6
You have to multiply by six because there are six possible arrangments:
i.e.
Red, Green, Blue
Red, Blue, Green
Green,Blue,Red
Green,Red,Blue
Blue,Green,Red
Blue,Red,Green
You'd probably get 1 out of 2 for what you wrote though
!