Edexcel Mathematics Higher Tier, November 2009 (1380/4H) (Paper 4, calculator)


Question 13 It helps to put the ratios into a table as below: Total


Piece one 2


Piece two 3


Piece three 4


9 180 cm


Then we can see that if the total is 9 then this has been multiplied by 20 to get 180 (180 ÷ 9 = 20) so we must multiply all the ratios by 20 as well.


Piece one 2


note 1 40


Piece two 3


note 2 60


note 1: 2 x 20 = 40 cm note 2: 3 x 20 = 60 cm note 3: 4 x 20 = 80 cm


The longest piece of wood would be 80 cm


Question 14 We know that the answer is between 3 and 4 so a good place to start would be to try 3.5. We will need to substitute 3.5 into the left hand side of the equation, then compare our answer to 60. If it is smaller then try again with a bigger value. If it is bigger then try again with a smaller value and so on.


x


3.5 3.6 3.7 3.8


x3


42.875 46.656 50.653 54.872


2x 7


7.2 7.4 7.6


x3 + 2x 49.875 53.856 58.053 62.472


comment too small too small too small too big


We can see that 3.7 is too small but 3.8 is too big. One of these is our answer. In order to work out which one the answer is closest to, we need to see how far out each is.


For 3.7 we are too small by 1.947 (60 – 58.053) For 3.8 we are too big by 2.472 (62.472 – 60) So we can see that 3.7 is closer.


The solution to 1 decimal place is 3.7 www.chattertontuition.co.uk 0775 950 1629 Page 5


Piece three 4


Total 9


note 3 80 180 cm


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