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Table 1 Relative weight of some physicochemical parameters and WHO water quality standards

From: An application of Water Quality Index (WQI) and multivariate statistics to evaluate the water quality around Maddhapara Granite Mining Industrial Area, Dinajpur, Bangladesh

Parameters WHO standards (2011) Weight (wi) Relative weight
\(\text{W}_{\text{i}} = \frac{{{\text{w}}_{1} }}{{\sum\nolimits_{{{\text{i}} = 1}}^{\text{n}} {{\text{w}}_{1} } }}\)
EC 500 4 0.097560976
TDS 500 5 0.121951220
TH 100 3 0.073170732
Ca2+ 75 3 0.073170732
Mg2+ 50 3 0.073170732
K+ 10 2 0.048780488
Cl 250 5 0.121951220
\({\text{HCO}}_{3}^{{ - }}\) 500 1 0.024390244
\({\text{SO}}_{4}^{{2{ - }}}\) 250 5 0.121951220
\({\text{NO}}_{3}^{{ - }}\) 45 5 0.121951220
\({\text{PO}}_{4}^{3 - }\) 0.5 1 0.024390244
PH 6.5–8.5 4 0.097560976
   \(\sum {w_{i} } = 41\) \(\sum {w_{i} } = 1.00\)