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2. ### General 2 paper

And worked solutions are here. Usual disclaimer - all care taken, no responsibility for errors, but I will try to correct them if you spot any.
3. ### 2 unit paper

Yeah, I did it that way too, but it wasn't as much fun. By the way, the method of expanding xn - cn IS part of the 2 unit course. It's part of the introduction to calculus and is usually done with limits and differentiating from first principles. Questions on first principles are rare, and so...
4. ### 2 unit paper

... and here are some worked solutions. The usual disclaimer applies. It would great if you could point out any errors.
5. ### Someone explain how bad is general maths scaled?

The scaling changes every year. If the paper is relatively easy (as last year's was), then it's naturally harder to get a higher scaled mark. If the paper is harder, then less people will get the high raw marks, so scaling isn't so harsh (so to speak). Look. The bottom line is that you have to...
6. ### Scale Down?

Well this is all well and good, but the way that this year's HSC marks will be scaled will vary from the way that last year's HSC marks were scaled. A few things to keep in mind. 1. A quick glance at the table shows me that unless you got 100% in 2 unit Maths, every mark got scaled down in that...
7. ### Some Questions from AIMO 2009

I didn't do it. I'm just trying the questions for fun (possibly not the best word).
8. ### Some Questions from AIMO 2009

Here are two questions which I'm stuck on. You might like to have a go, and perhaps post the solutions. 8. In ∆ABC, angle ABC = 138° and angle ACB = 24°. Point D is on AC so that angle BDC = 60° and point E is on AB so that angle ADE = 60°. If angle DEC = x°, find the value of x. 9. Let...
9. ### Depreciation

S = V0(1 – r)n We need S = 1000, V0 = 6000 and r = 33% = 0.33 S = V0(1 – r)n 1000 = 6000(0.67)n Divide both sides by 6000 1/6 = (0.67)n Now a number of ways of going from here. 1. Guess and check (or trial and error) 2. Use logs 3. Use solver function on graphics calc Let's use...
10. ### Will they do this with Simpsons Rule?

You'll be asked to apply Simpson's Rule twice. No more or less than that. Certainly no complications. Trapezoidal rule won't come into it.
11. ### Proportional to sqrt ??

h is proportional to √n .: h = k x √n , where k is the constant of proportionality When h = 35, n = 2000 .: 35 = k x √2000 k = 35/√2000 So put this in our formula. h = 35/√2000 x √n Now, when n = 10000: h = 35/√2000 x √10000 = 78.26237921 = 78 cm
12. ### Box and whisker plot HELP

To draw a box plot, you need the five number summary (Minimum, 1st Quartile, Median, 3rd Quartile and Maximum). The question gives us the minimum (140 cm) and maximum (190 cm). We'll have to find the rest ourselves. There are 60 people altogether (not 70, be careful). So the median is at...
13. ### General Maths

Yes that is true, because they don't want you using all those useful calculator programmes that you have programmed into your calculator to help you cheat! If it's a Casio 9850GB or 9860, then it will certainly default to Radians as the angle measure and you'll need degrees. So as soon as you...
14. ### What formulas are not on the formula sheet?

Probably the most useful formulae not on the sheet are all those formulae for Area of Plane shapes, such as area of a circle, and especially area of a trapezium A = h/2(a + b).
15. ### Determining which annuity formula to use

For Future Value Formula: Look for words like "how much will the investment be worth after 20 years" For Present Value Formula: Look for words like "what amount does s/he have to invest now so that ..." The present value formula that you use will depend on the information given. Remember...
16. ### Help with probability

It's not really an easy question! The best way of tackling this question is to draw a tree diagram and write the probabilities on each of the branches. P(blue then blue) = 15/20 x 14/19 = 21/38 P(blue then red) = 15/20 x 5/19 = 15/76 P(red then blue) = 5/20 x 15/19 = 15/76 P(red then red)...
17. ### Help with what seems a basic question...

Remember that the interest is compounded monthly, so everything needs to be done in months. r = 0.5% per month = 0.005 n = 7 years = 84 months A = M[(1+r)n–1 / r] = 125 x [(1+0.005)84–1 / 0.005] = 125 x [(1.005)84–1 / 0.005] = 125 x [(1.005)84–1 / 0.005] = \$13 009.24