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IGCSE MATHS DOUBTS HERE !!!!

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astarmathsandphysics:
no idea

Galleria:
http://www.xtremepapers.net/CIE/Cambridge%20IGCSE/0580%20-%20Mathematics/0580_w09_ms_22.pdf

Q 21 b .
I don't get it . how is it 960 ?

elemis:
One moment

elemis:
The area under a graph is equal to the distance covered.

The car travels faster than the truck from 15 s to 55 s

Hence, I 've split the relevant area into two trapeziums. One red and one blue.

Using the area of a trapezium formula for the red one :

0.5* (12+36)*30 = 720

Using the same formula for the blue one :

0.5 * (36+12)*10 = 240

Hence, 240 + 720 = 960 m

The area of a trapezium is given by this formula :

0.5 (sum of the length of parallel side) * perpendicular distance between the two parallel sides

Deadly_king:

--- Quote from: Kimo Jesus on October 15, 2010, 07:48:43 am ---ok but for the next one , the answer in my book says 12 years why?

6000 x 1.11^n = 18000
 1.11^n= 3

thergfore log 3/ log 1.11

=10.5

and anywy the anwer in the book says 12 and 6000 x 1.11^12 =  20000 +

--- End quote ---

You made a little mistake there dude. It actually is similar to a general progression ;)

The required solution :
6000 x 1.11(n-1) = 3(6000)

Simplify it and you'll be getting n = 11.5 which can be taken as 12. But the best answer is 11.5

Same principle is applied for question 3 and 1.
3) 2 x 1.21(n-1) = 20

You just need to simplify and you'll get n = 13

1) 100 X 1.1(n-1) = 2(100) -----> n = 8.27 which can be taken as 8 ;)

Hope it helps :)

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