OCR Further Additional Pure 2019 June — Question 7

Exam BoardOCR
ModuleFurther Additional Pure (Further Additional Pure)
Year2019
SessionJune
TopicNumber Theory

7 The points \(P \left( \frac { 1 } { 2 } , \frac { 13 } { 24 } \right)\) and \(Q \left( \frac { 3 } { 2 } , \frac { 31 } { 24 } \right)\) lie on the curve \(y = \frac { 1 } { 3 } x ^ { 3 } + \frac { 1 } { 4 x }\).
The area of the surface generated when arc \(P Q\) is rotated completely about the \(x\)-axis is denoted by \(A\).
  1. Find the exact value of \(A\). Give your answer as a rational multiple of \(\pi\). Student X finds an approximation to \(A\) by modelling the arc \(P Q\) as the straight line segment \(P Q\), then rotating this line segment completely about the \(x\)-axis to form a surface.
  2. Find the approximation to \(A\) obtained by student X . Give your answer as a rational multiple of \(\pi\). Student Y finds a second approximation to \(A\) by modelling the original curve as the line \(y = M\), where \(M\) is the mean value of the function \(\mathrm { f } ( x ) = \frac { 1 } { 3 } x ^ { 3 } + \frac { 1 } { 4 x }\), then rotating this line completely about the \(x\)-axis to form a surface.
  3. Find the approximation to \(A\) obtained by student Y . Give your answer correct to four decimal places.