Apps. and Interpretation for IBDP Maths Ebook 1 | Page 15

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Example
Paper 1 – Rounding and Percentage Error
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(2sin( z))( x�17)
A � , where x � 10 , y � 0.5 and z � 60 .
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64xy
(a) Calculate the exact value of A .
(b) Give your answer to A correct to two significant figures.
(c) Write down an inequality representing the error interval of this estimate.
Casey estimates the value of A to be 0.055.
[1]
[1]
[2]
(d)
Calculate the percentage error in Casey’s estimate.
[2]
Solution
(a) 0.05625 A1 N1
[1]
(b) 0.056 A1 N1
[1]
(c) 0.0555 � A � 0.0565
A2 N2
[2]
(d) The percentage error
0.055 � 0.05625
� � 100%
(A1) for correct substitution
0.05625
� 2.222222222%
� 2.22%
A1 N2
[2]
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