in Water and Waste Water Quality and Treatment retagged by
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A water sample is analyzed for coliform organisms by the multiple-tube fermentation method. The results of confirmed test are as follows:

$\begin{array}{|cl|cI|cI|}\hline
&\textbf{Sample size  $\text{(mL)}$} & \textbf{Number of positive}& \textbf{Number of negative} \\ && \textbf{results out of $5$ tubes} &\textbf{results out $5$ tubes}\\ \hline &\text{$0.01$} & \text{$5$} & \text{0} \\ \hline &\text{$0.001$} & \text{$3$} & \text{$2$}\\ \hline &\text{$0.0001$} & \text{$1$} & \text{$4$}  \\ \hline \end{array}$

The most probable number $\text{(MPN)}$ of coliform organisms for the above results is to be obtained using the following $\text{MPN}$ Index.

$\text{MPN}$ Index for Various Combinations of Positive Results when Five Tubes used per Dilution of $10.0 \text{ mL}$, $1.0\text{ mL}$ and $0.1 \text{ mL}$
Combination of positive tubes $\text{MPN}$ Index per $100$ $\text{mL}$
$0 – 2 – 4$ $11$
$1 – 3 – 5$ $19$
$4 – 2 – 0$ $22$
$5 – 3 – 1$ $110$

 The $\text{MPN}$ of coliform organisms per $\text{100 mL}$ is

  1. $1100000$
  2. $110000$
  3. $1100$
  4. $110$
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