Maths: good luck for a good answer

http://qualifications.pearson.com/content/dam/pdf/GCSE/Mathematics%20B/2010/Exam%20materials/5MB1H_01_que_20131106.pdf

Q15: a little help pleease; quite confusing....

Reply 1

the bear

you need to find the frequencies first ( = area of boxes )

then figure out 25% of the total frequency ( = 1/4 )

then starting at the left build up the area until it equals the figure you just worked out.

Reply 2

pxnda

1) find frequencies of all the bars (frequency denist*class width)-area of each box
2)then find 25% of total frequency
3) from bars use the areas to find out where 25% is

Reply 3

username1310825

can you plese please do the first bar as an example: just want to make sure im on the right path

Reply 4

username1310825

can you guys plez explain in detail: i am getting mixed with claculating the freq-density and the class-width or the area and the class-width

Thnks

Reply 5

pxnda

Original post by Jeeves CP

can you guys plez explain in detail: i am getting mixed with claculating the freq-density and the class-width or the area and the class-width

Thnks

18*5=90
5*35=175
20*7=140
15*12=180
15*7=105
total=690
(area of all bars)
25%of 690=172.5
so it is in the second bar
172.5-90=82.5
172.5/82.5=2.12 so apx 2 boxes after 1st bar
which is 55
not sure if its correct but worth a try :colondollar:

Reply 6

username1310825

Original post by pxnda

its right!
i get it....one questions....
-->why do you do 172.5/82.5?

Reply 7

username1310825

also why how did you find out that 172.5 is in the 175 bar and not the 180 bar?

thnks

Reply 8

CharmingCat

Thanks! Is it possible for you to get hold of a Foundation Tier paper too, please? It could save my life when I sit my mocks in several weeks' time!

Reply 9

pxnda

Original post by Jeeves CP

also why how did you find out that 172.5 is in the 175 bar and not the 180 bar?

thnks

because you want to find what each box is worth and because you start from the left & we need to get to 172.5
so 90 is in the first so we only need another 82.5 to get to our total so it cannot be beyond the second bar :wink:

Reply 10

username1310825

Original post by CharmingCat

Thanks! Is it possible for you to get hold of a Foundation Tier paper too, please? It could save my life when I sit my mocks in several weeks' time!

sorry?

Reply 11

username1310825

Original post by pxnda

how do you figure out the scale of the frequency density

Reply 12

username1310825

why do you 172.5/82.5?

Reply 13

username1310825

Original post by pxnda

i did:

25% x (18x5)+(10x35)+(7x20)+(12x15)+(5x7) = 198.75
okay so u do 198.75 - 90 to find out where the first quarter (25%) is.
now can you tell me what to do and WHY?

thanks so much for your help so far.. how to give rep points?!?

Reply 14

pxnda

Original post by Jeeves CP

now we know the first column has 90
second column has 350
so it MUST be in the second and cannot be beyond this point as 90+350>198.75
so we do 198.75-90=108.75(sorry i got my calculations slightly wrong last time)
now we got to find where t is in that block so divide 350 by 108.75 which gives you apx 3 so its 54t+3 boxes which is 55.5 so apx 55
as i said im not sure if its correct.