Use simultaneous equations with variable a and d.
Then when you solve for a and d just find the sum when n=20
i.e.
a+5d=23
a=23-5d (1)
10/2(2a+9d)=210 (2)
sub (1) in (2)
Solve.
Re: 2012 Year 9 &10 Mathematics Marathon
That's true. Some people read solutions and think they understand, but when you give them a similar question, they have no idea.
Re: 2012 Year 9 &10 Mathematics Marathon
A mushroom farmer has sent an order of 70 kg of mushrooms to the markets in standard cases. If he had used larger cases, each capable of holding 2 kg more, he would have used 4 fewer cases.
What is the capacity (in kg) of the standard case?
Re: 2012 Year 9 &10 Mathematics Marathon
It's called LaTeX. http://www.codecogs.com/latex/eqneditor.php <you can try it out here
To post with it on here [ TEX ] *put code in here* [ / TEX ] without any spaces in the brackets.
You'll~get~used~to~it
Re: 2012 Year 9 &10 Mathematics Marathon
Another thing you should keep in mind is that the side length of an equilateral triangle inscribed in a circle of radius R is R\sqrt3. This can be proved later with calculus. So in this case, R*sqrt3=1, therefore R=1/sqrt3 (0.577...)
Just an...
80 on all those subjects is about 82-84 ATAR.
Your looking at about 85 for every 2U subject there and about 40 for every one unit subject to break the 90 ATAR mark.
Or another way to look at it is that you need an average scaled mark of 37/50 per unit to get 90 ATAR. Go to an estimator and...
Here is another good one:
The lengths of the sides of the octagon are 1, 2, 3, 4, 5, 6, 7 and 8 units in some
order. Find the maximum area of the hexagon (square units).
It depends on what you are looking for. Dot Point is mainly questions based on syllabus points while Excel is more of a summary with basic questions to test your knowledge.