RuneScape:Grand Exchange Market Watch/Adjustments (23 July 2013)

23 July 2013

Adjusted index: Discontinued Rare Index Adjustment date: 23 July 2013 Affected templates: Template:GE Discontinued Rare Index and Template:GE Discontinued Rare Index/Diff Added item(s): Crown of Seasons Removed item(s): None Items before adjustment: 17 Items after adjustment: 18 Divisor before adjustment: 15.1547 Divisor after adjustment: 15.2129 Item Base date Base price Price on adjustment date Comments Christmas cracker 31 December 2008 688,800,000 2,147,483,557 Unchanged Blue partyhat 340,100,000 2,147,483,647 Green partyhat 114,800,000 1,845,813,270 Purple partyhat 83,100,000 1,514,338,96 Red partyhat 129,400,000 2,100,264,784 White partyhat 183,300,000 2,147,483,598 Yellow partyhat 96,300,000 1,607,195,89 Pumpkin 5,300,000 177,606,966 Easter egg 4,300,000 82,884,794 Blue h'ween mask 12,800,000 169,489,376 Green h'ween mask 10,600,000 129,808,159 Red h'ween mask 17,300,000 234,599,317 Santa hat 14,800,000 149,818,733 Disk of returning 4,700,000 226,927,013 Half full wine jug 31,100,000 320,604,356 Fish mask 29 September 2012 4,555,462 1,446,274 Christmas tree hat 20 January 2013 2,295,576 26,024,637 Crown of Seasons – – 8,307,542 Added item Calculations From the old divisor obtained from the templates: ${div}_{\text{old}} = 15.1547$ We need to calculate a new divisor: ${div}_{\text{new}} = {div}_{\text{old}} \times \frac{\sum \left ( \frac{p}{q} \right )_{\text{new}}}{\sum \left ( \frac{p}{q} \right )_{\text{old}}}$ To calculate the new divisor, we need to find: $\begin{align} \sum \left ( \frac{p}{q} \right )_{\text{old}} & = \text{sum of ratios prior to change} \\ & = \frac{2,147,483,557}{688,800,000} + \frac{2,147,483,647}{340,100,000} + \frac{1,845,813,270}{114,800,000} + \dots + \frac{26,024,637}{2,295,576} \\ & = 260.57227963 \text{ (up to 8 d.p.)} \end{align}$ And also: $\begin{align} \sum \left ( \frac{p}{q} \right )_{\text{new}} & = \text{sum of ratios prior to change} - \text{sum of removed ratios} + \text{sum of added ratios} \\ & = \sum \left ( \frac{p}{q} \right )_{\text{old}} - \text{sum of removed ratios} + \text{number of added items} \\ & = 260.57227963 - 0 + 1 \\ & = 261.57227963 \text{ (up to 8 d.p.)} \end{align}$ Thus, the new divisor is: $\begin{align} {div}_{\text{new}} & = {div}_{\text{old}} \times \frac{\sum \left ( \frac{p}{q} \right )_{\text{new}}}{\sum \left ( \frac{p}{q} \right )_{\text{old}}} \\ & = 15.1547 \times \frac{261.57227963}{260.57227963} \\ & = 15.2129 \text{ (4 d.p.)} \end{align}$