TheRedDevil10 wrote: » Paper 2 According to the syllabus:Constructions 16. Construct the circumcircle and circumcentre of a given triangle http://www.mathopenref.com/constcircumcircle.html 17. Construct the incircle and incentre of a given triangle http://www.mathopenref.com/constincircle.html 18. Construct an angle of 60 degrees http://www.mathopenref.com/constangle60.html 19. Construct a tangent to a circle at a given point on it http://www.mathopenref.com/consttangent.html 20. Construct a parallelogram given the lengths of the sides and measures of the angles https://www.youtube.com/watch?v=wVmDKqhC47Q 21. Construct the centroid of a triangle http://www.mathopenref.com/constcentroid.html
zvseire wrote: » i guessed d anybody know the correct answer?
martmikey wrote: » Could someone please tell me how to do this question: Helen has enough credit to download three songs from the internet. There are seven songs that she wants. (i) How many different possible selections of three songs can she make? (ii) If there is one particular song that she definitely wants, how many different selections can she now make? PLEASE
smtp95 wrote: » For part (i) she can buy 3 but there are seven choices. So imagine you have 3 boxes for the songs she can buy. For the first box she has seven choices, for the second she has six and for the third she has five. 7X6X5= 210 different selections For part (ii). Imagine one of those 3 boxes for the songs is filled, you only have one choice there. So in the second box you will now have 6 possible choices and for the third you will have five. 1X6X5=30 selections I hope this helps. If you have Active Maths they cover this chapter very well in the book
FlyingIrishMan wrote: » I got a markup of around 75% too. The total he made from selling 22 sets at normal prices + the 3 remaining sets discounted at 20% was around 2100. And then I just got the percentage difference between the original 1250 and the new total with the discounted sets.
martmikey wrote: » Thanks... Thats what i thought but when i looked up the marking scheme.. This was the answer: How many different possible selections of three songs can she make? = 35 (ii) If there is one particular song that she definitely wants, how many different selections can she now make? = 15
smtp95 wrote: » Hmmm... :P I think we're right because with seven choices and three possible songs there would be a lot of possible combinations, not just 35. But if that's what the marking scheme says well... Damn permutations
aleatorio wrote: » HL student here, It's because the 210 combinations are including the different orders of the songs, as in 1,2,3 and 3,1,2 - they're the same songs downloaded, just a different order, so 210 is not correct The correct answer is 35 because 7choose3 is 7! Divided by 3!((7-3)!) The formula for nchooser is n!/(r!((n-r)!) Which gives 35 Then for the second part, it's 6choose2 because one has already been chosen, which using the above formula gives 15
Dee15 wrote: » Just realised I forgot to write in my calculator information on the front of the paper, is that important?!
Rainydays212 wrote: » Do you think they will give us an easier paper two? So nervous for Monday..:/
onethreefive wrote: » My future is relying on the hope that it will be easier..
miissjuly wrote: » Guys I just checked the answers got around a B on Paper 1 so hopefully I can get an A with paper 2. As if 60/50 points is going get me 550 points.. *sighs*
smtp95 wrote: » Ahh alright, I get it now. Thanks. That's what I do OL for :P