FANDOM


30 August 2014
Item Base date Base price Price on adjustment date Comments
Air rune 15 December 2007 11 19 Unchanged
Mind rune 10 6
Water rune 15 26
Earth rune 11 14
Fire rune 10 22
Body rune 9 8
Cosmic rune 140 245
Chaos rune 102 41
Nature rune 258 263
Law rune 304 281
Death rune 299 163
Astral rune 132 245
Blood rune 336 261
Soul rune 335 153
Armadyl rune 14 October 2011 1,817 389
Steam rune 37 Added item
Mist rune 348
Dust rune 66
Smoke rune 314
Mud rune 775
Lava rune 49

Calculations

From the old divisor obtained from the templates:

$ {div}_{\text{old}} = 15.5671 $


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{19}{11} + \frac{6}{10} + \frac{26}{15} + \dots + \frac{153}{335} + \frac{389}{1,817} \\ & = 16.36670735 \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} \\ & = 16.36670735 - 0 + 6 \\ & = 22.36670735 \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}}} \\ & = 15.5671 \times \frac{22.36670735}{16.36670735} \\ & = 21.2740 \text{ (4 d.p.)} \end{align} $