Melody

It is an upside down sine cuve with a period of    $$\frac{2\pi}{\pi/2}=\frac{2*2\pi}{\pi}=4$$

Here is the graph

$$\sqrt8=\sqrt{4*2}=2\sqrt2$$

Yes that is corrrect.  Power users have a hollow star with their name.  Moderators have a solid star.  

You have told me that before Chris but I keep forgetting!     

There is a divide in there Afrikagurl   :(

Nor to worry - I'll give you some points anyway :)

Thanks Alan,  I have not quite got my head around your answer yet, I will try some more:/

Einstein, does 'exacly' mean 'thank you' to you?

OR  did you already know the answer and thought Alan, or someone else, needed some brain food?

I will certainly admit that it was a excellent question. :)

I don't understand the question.  Maybe I should but I don't.

Do you mean that the mark out of 40 and the mark out of 100 are just added together and the total out of 130 is turned into a percentage?

$$\\\frac{20.4+x}{130}=0.40\\\\
20.4+x=52\\\\
x=52-20.4\\\\
x=31.6$$

It doesn't matter MG,

Who would lant to count all those cm anyway!   Plus you got it our eventually  

Thanks Alan 

Thank you Mistress Feather :)

Hi MG

Maybe I just misunderstood what you meant - you have to be very precise in mathematics :)