VCE Further Maths Exam 2 - 04/11/19 - Discussion/Questions/Solutions

[pugs]

for the residual question in core, did anyone also say that the assumption was that the relationship was non-linear, but it was wrong because the association is actually linear? (the r value ~0.966 is v high which means that it's linear - i didn't include this in the answer by the way but for reference)

[PhoenixxFire]

I already lost 5 marks in exam 2, 1 mark in exam 1, and my sac average isnt that good. I think I'm have no chance of getting 40. Now I have to rely on Methods so so I can get a decent ATAR. I'm so frustrated right now, can't get myself to study for methods.

Definitely can still get a 40 with that! As long as your sac marks aren't below about 92% after scaling, all of your GA's will be A+ which will get you an A+. Can likely still get a 40 with SAC scores slightly lower than that because your exam 1 score is a high A+.

i lost 5 marks in exam 1, and got full marks in exam 2, does that mean i can get above a 40?

Yep. Your exam 1 score is just below an A+ but your exam 2 score will compensate for that.

[Amnilauv]

for the residual question in core, did anyone also say that the assumption was that the relationship was non-linear, but it was wrong because the association is actually linear? (the r value ~0.966 is v high which means that it's linear - i didn't include this in the answer by the way but for reference)

Question 1 asked what the assumption was, which was linear

However, judging by the residual plot, it clearly was not linear because you could see a distinct pattern, which is parabolic.
Question 2 stated that it did not support the assumption that it was linear because there was a clear pattern, hence, it was non-linear.

[angelina.s]

What did you guys get for core when it asked for the number of ays the maximum temp was less than the median of the min? I got 1

Also what'd you guys get for the finance question for the total interest (the reducing balance loan of 50000, fortnightly

i got one day too, also i got 45246.67 for the total interest question (i'm not sure if this is the same one as what your asking about bc that exam was a blur but i think it was the one that had a starting value of 350000)

[pugs]

Question 1 asked what the assumption was, which was linear

However, judging by the residual plot, it clearly was not linear because you could see a distinct pattern, which is parabolic.
Question 2 stated that it did not support the assumption that it was linear because there was a clear pattern, hence, it was non-linear.

but the r value was very high and it was the same set of data so wouldn't it have to be a linear association? (i also thought that the residual plot didn't have a distinct pattern sigh)

[ImamB1]

When you had to calculate the residual for 3pm and 9am or something like that did you get 1(to the nearest whole number )?

[Jim_Bob]

When you had to calculate the residual for 3pm and 9am or something like that did you get 1(to the nearest whole number )?

With residuals, you want to find the predicted y value and actual y value. They gave us the x-value, so we could work out the predicted y-value. However, we needed to look at the scatterplot to find the ACTUAL value

[Jashy]

With residuals, you want to find the predicted y value and actual y value. They gave us the x-value, so we could work out the predicted y-value. However, we needed to look at the scatterplot to find the ACTUAL value

nope. I got approx 2.6 so therefore rounded to whole = 3.

[Amnilauv]

but the r value was very high and it was the same set of data so wouldn't it have to be a linear association? (i also thought that the residual plot didn't have a distinct pattern sigh)

I'm not amazing at further, but I don't think r values have anything to do with residuals (or at least not much to do with it).
We were looking at the distribution of the dots on the graph, and we can see that the dots followed a parabolic shape.
Just a note that if there is a clear pattern of some sort, then the association will be non-linear , vise versa for no clear pattern.

From the get go, once you saw the residual graph, you would see that it is non-linear (because there was a pattern). The second question asked that it did not support the assumption of question 1 (which, I'm pretty sure any questions that ask 'what is the assumption?' will always be that it is linear), so you would know that it wouldn't be linear because it stated that it didn't support the assumption.

nope. I got approx 2.6 so therefore rounded to whole = 3.

I got 105-102 = 3 for the residual

[Jim_Bob]

nope. I got approx 2.6 so therefore rounded to whole = 3.

I'm right though

[Amnilauv]

I'm right though

Yes, you had to use the equation to find the predicted value, and then for actual value you had to use the graph given (so the value of the actual value found on the graph was 105)

[Jim_Bob]

Yes, you had to use the equation to find the predicted value, and then for actual value you had to use the graph given (so the value of the actual value found on the graph was 105)

Ahaha yes! I was just a bit confused why you quoted my initial response with "nope." Scared me

[Arthurmorgan]

The residual question answer:

[Jashy]

The residual question answer:

yep agreed

[Tadd12345]

When you had to calculate the residual for 3pm and 9am or something like that did you get 1(to the nearest whole number )?

A lot of people got that but it was wrong. The answer is meant to be 1015-1012.4= 2.6 rounded to 3.
U misinterpreted the question, the value 1013 they gave u wasn’t the ACTUAL value, but instead a pressure point at 9am, which u then put in the regression line to calculate the predicted, and compare it with the actual value u find on the scatterplot, which was 1015