AQA D1 2012 January — Question 8

Exam BoardAQA
ModuleD1 (Decision Mathematics 1)
Year2012
SessionJanuary
TopicInequalities

8 Four distinct positive integers are \(( 3 x - 5 ) , ( 2 x + 3 ) , ( x + 1 )\) and \(( 4 x - 13 )\).
  1. Explain why \(x \geqslant 4\).
  2. The four integers are to be sorted into ascending order using a bubble sort. The original list is
    \(\begin{array} { c c c c } ( 3 x - 5 ) & ( 2 x + 3 ) & ( x + 1 ) & ( 4 x - 13 ) \end{array}\)
    After the first pass, the list is
    \(( 3 x - 5 ) \quad ( x + 1 ) \quad ( 4 x - 13 ) \quad ( 2 x + 3 )\)
    After the second pass, the list is
    \(( x + 1 )\)
    \(( 4 x - 13 )\)
    \(( 3 x - 5 )\)
    \(( 2 x + 3 )\)
    After the third pass, the list is
    \(( 4 x - 13 ) \quad ( x + 1 )\)
    \(( 3 x - 5 )\)
    ( \(2 x + 3\) )
    1. By considering the list after the first pass, write down three inequalities in terms of \(x\).
    2. By considering the list after the second pass, write down two further inequalities in terms of \(x\).
    3. By considering the list after the third pass, write down one further inequality in terms of \(x\).
  3. Hence, by considering the results above, find the value of \(x\).
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