Contamination of heavy metals, particularly Mercury and Arsenic, were investigated in mining-impacted communities that use traditional methods of mining gold. Three sitios were included in the study area namely Sitio Masigasig, Sitio Magilas, and Sitio Maligalig. During fieldwork, an equal number of samples were collected in strategic points distributed in each Sitio and were tested for Hg and As concentrations using a portable heavy metal analyzer. In the absence of a local standard, environmental engineers working on the project used the Australian and New Zealand Standards. It was found that:

• 15% of samples from Sitio Magilas exceeded both Hg and As threshold limits
• 40% of samples from Sitio Masigasig exceeded the Hg threshold limit only
• 25% of samples from Sitio Magilas exceeded the Hg threshold limit
• 60% of samples from Sitio Magilas exceeded As threshold limit
• 50% of samples from Sitio Maligalig exceeded As threshold limit only

1. What proportion of the total number of samples exceeded the Hg threshold level?
2. Whatproportion of the total number of samples exceeded the As threshold level?
3. Whatproportion of the total number of samples failed any provisions of Australia and New Zealand Standards for Hg or As concentrations in soil?
4. Whatproportion of samples that failed the standards for either Hg or As are from Sitio Magilas?