D1 - most difficult questions?

which syllabus are you doing for D1 ?

I was just coming back to edit that in hoping nobody had noticed, sorry! I'm doing Edexcel.

some people find dummies hard to understand when drawing activity networks.

Ohh, that's a good one, thanks. I'd forgotten about those, I know I had difficulty with them when learning about them. I'd rep you if I could but I've done that too recently to do it again.

Any more you can think of?

Simplex used to be in the D1 but it was removed

But I'm doing D2 as well.

The maximum number of iterations on a binary search is log2(n), I think you also have to know maximum iteration on a bubble sort which is something like 1/2 n(n+1)

That makes sense, though wouldn't they be Binary:
$\lceil log_2 (n) \rceil$
and Bubble:
$\dfrac{n(n-1)}{2}$

First one because the log function sometimes doesn't give integer values and the second one is just an adjustment of the triangle number formula you gave.

Do we need to know the same thing for quick sort too?

...

Yourself or someone doing Edexcel D1 might like to have a look at this thread, as the OP is struggling there.

I saw that thread but thought I was doing something wrong. My method was:

The gradient obviously has to be between -2 (the line AB) and -4 (the line CD), so $\frac{1}{4} < k < \frac{1}{2}$.

I thought I must be doing something wrong if that's a 6 marker in one line, but it's the same answer BinaryJava got...

Mark scheme used a different, algebraic, approach - see below:
Edit: Different to what I was thinking.

Uhh, wow. That's a really complicated method. Will you lose marks for using a graphical approach, like the one I did, in the exam?

I'd be guessing; possibly someone like Mr M may be able to advise.

Who's Mr M?

Truely, I am shocked you've not heard of Mr M.

He's not posted as much recently on the maths forum, but seems to be in the know on the ins and outs of exams, particularly mathematics.

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