3/4 Further questions

[FlorianK]

2 questions from the 2010 VCAA exam 1. http://www.vcaa.vic.edu.au/vcaa/vce/studies/mathematics/further/pastexams/2010/2010furmath1-w.pdf

Core question 12:
It's a graph so I can't really post the question:
My answer would be C, the examiner report is saying D. I have no idea why, I'm really sure that it should be C.

Module 2 question 8:
Question 8
Dan takes his new aircraft on a test flight.
He starts from his local airport and flies 10 km on a bearing of 045 ° until he reaches his brother’s farm.
From here he flies 18 km on a bearing of 300 ° until he reaches his parents’ farm.
Finally he flies back directly from his parents’ farm to his local airport.
The total distance (in km) that he flies is closest to
A. 37
B. 42
C. 46
D. 59
E. 61


I got the right answer in the end C (46).
However, I drew the triangle.
With
A=45° B=75° C=60°
a=18km and c= 10km

Using sine rule my answer was:
(sin(75)/sin(45))*18=24.6
24.6+10+18=53km ??

Using cos-rule i got
b=(10²+18²-2*18*10*cos(75))^.5=18.2
18.2+10+18= ~46

Where was my mistake when I used sine rule?

thx Florian

[b^3]

Remember mean will be the average, median will be the 'middle' number

So we have
362 375 360 385 377
Put them in order
360 362 375 377 385

Now the median will be 375, so that is D

For the other question.
With your sine rule, as 18 km will take you to further than directly north of the starting point, the angle wont be 45 degrees as it isn't to the straight up, its better not to use the sine rule in that case. Ill see if I can attach a diagram in a minute.

Also this is one of the exams I sat

EDIT: Image added, bit rushed but should give you the idea. The red bit is the angle that is missing when you did the calculation, instead of finding it its better to use the other method that you used.

EDIT2: there was an error in the image as Florian has pointed out, fixed it now

[FlorianK]

I was so sure I got the right answer, but of course I didn't read the question.

thx

The 30 at the bottom should be a 45, but anyways. I see now why I can't use sine rule. thx alot

[FlorianK]

How much working out do we need to show in exam 2?
For example a question is:
How long (in minutes) will it take for Sally to pass Bruce's house? (1 mark)
Is it ok if I only write the answer? "231 minutes"

[Bhootnike]

Looking at marking scheme,  id say so.
Also in further you have the calculator in both exams.  So they wouldn't  expect much for 1 mark questions

[pi]

I always liked to show one step more than the marks (at least) if possible, just to be safe

[FlorianK]

Thx.

When it's not stated to how many decimel places do we need to round of.
One of the answers in the exam i'm correcting at the moment had the answer "11/1.507~7.3". The answers say 7.299.
So always to 3 decimals or is there a connection to the question like in chemistry or is one decimal ok?

[Stick]

I'm pretty sure in Further that you're always told how many decimal places to round to, because it's one of the major weaknesses of the cohort as a whole (check the assessment reports and see for yourself). If you round to the incorrect number of decimal places in the exam, you will only lose 1 mark throughout the whole paper, and not each time, like in Methods and Specialist. Also, while examiners are lenient on using previous rounded answers in proceeding questions, it is worth getting into the habit of using unrounded figures instead. In the case that the exact value is not reasonable to work with, round to four decimal places.

[max payne]

How much working out do we need to show in exam 2?
For example a question is:
How long (in minutes) will it take for Sally to pass Bruce's house? (1 mark)
Is it ok if I only write the answer? "231 minutes"

Of course. It would even be sufficient to just write "231" in this question since they stated (in minutes). Questions worth 1 mark only require one statement

[FlorianK]

A cereal retailer obtains a particular type of cereal from three different types of suppliers P,Q,R.
                                  Sultanas   
Supplier P                                  15%      
Supplier Q                   19%      
Supplier R                   12%      
Minumum of ingredient needed 14%      

The total amount of cereal required is 100kg
If x= the number of kilograms from supplier P
And y= the number of kilograms from supplier Q
What is the constraint inequation caused by the restriction on sultanas?