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O-LevelAdditional MathematicsLogarithmic and exponential functions4037/22 · May/June 2012 · Q78 Marks

The table shows experimental values of variables x and y. X | 5 | 30 | 150 | 400 y | 8.9 | 21.9 | 48.9 | 80.6

  1. (i)By plotting a suitable straight line graph, show that y and x are related by the equation y = axᵇ, where a and b are constants.[4]
  2. (ii)Use your graph to estimate the value of a and of b.[2]
  3. (iii)Estimate the value of y when x = 100.[2]

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Mark scheme

Marking points from the official mark scheme (May/June 2012). The mark or mark type is shown in brackets.

  1. [B1] (i) ln y = ln a+b ln x OR lg y = lg a + b lg x may be implied
  2. [M1] (i) Plot ln y / lg y against ln x / lg x with attempt at linear scale
  3. [A2, 1, 0] (i) (Marks for points and line on graph NOT for table)
  4. [M1] (ii) Calculates gradient of straight line log graph
  5. [A1] (ii) b = 0.5±0.03
  6. [M1] (ii) Intercept is ln a or lg a on straight line log graph
  7. [A1] (ii) a = 4±0.3
  8. [M1] (iii) Uses suitable graph or formula
  9. [A1] (iii) 32 to 49

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About this question

Topic
Logarithmic and exponential functions, O-Level Additional Mathematics (syllabus 4037). Structured question, 8 marks.
Source
O-Level Additional Mathematics, May/June 2012 Paper 2 Variant 2, question 7.

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