RuneScape:Grand Exchange Market Watch/Adjustments (29 September 2012)

29 September 2012

Adjusted index: Discontinued Rare Index Adjustment date: 29 September 2012 Affected templates: Template:GE Discontinued Rare Index and Template:GE Discontinued Rare Index/Diff Added item(s): Fish mask Removed item(s): None Items before adjustment: 15 Items after adjustment: 16 Divisor before adjustment: 15.0000 Divisor after adjustment: 15.0826 Item Base date Base price Price on adjustment date Comments Christmas cracker 31 December 2008 688,800,000 2,146,908,554 Unchanged Blue partyhat 340,100,000 2,147,483,647 Green partyhat 114,800,000 1,124,859,082 Purple partyhat 83,100,000 895,254,988 Red partyhat 129,400,000 1,232,179,013 White partyhat 183,300,000 1,652,939,303 Yellow partyhat 96,300,000 948,567,763 Pumpkin 5,300,000 165,935,075 Easter egg 4,300,000 56,837,419 Blue h'ween mask 12,800,000 112,172,382 Green h'ween mask 10,600,000 90,439,249 Red h'ween mask 17,300,000 149,074,067 Santa hat 14,800,000 116,884,816 Disk of returning 4,700,000 171,076,782 Half full wine jug 31,100,000 261,000,577 Fish mask – – 4,555,462 Added item Calculations From the old divisor obtained from the templates: ${div}_{\text{old}} = 15.0000$ 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: $\begin{align} \sum \left ( \frac{p}{q} \right )_{\text{old}} & = \text{sum of ratios prior to change} \\ & = \frac{2,146,908,554}{688,800,000} + \frac{2,147,483,647}{340,100,000} + \frac{1,124,859,082}{114,800,000} + \dots + \frac{261,000,577}{31,100,000} \\ & = 181.52107486 \text{ (up to 8 d.p.)} \end{align}$ And also: $\begin{align} \sum \left ( \frac{p}{q} \right )_{\text{new}} & = \text{sum of ratios prior to change} - \text{sum of removed ratios} + \text{sum of added ratios} \\ & = \sum \left ( \frac{p}{q} \right )_{\text{old}} - \text{sum of removed ratios} + \text{number of added items} \\ & = 181.52107486 - 0 + 1 \\ & = 182.52107486 \text{ (up to 8 d.p.)} \end{align}$ Thus, the new divisor is: $\begin{align} {div}_{\text{new}} & = {div}_{\text{old}} \times \frac{\sum \left ( \frac{p}{q} \right )_{\text{new}}}{\sum \left ( \frac{p}{q} \right )_{\text{old}}} \\ & = 15.0000 \times \frac{182.52107486}{181.52107486} \\ & = 15.0826 \text{ (4 d.p.)} \end{align}$