explain in detail that how water sample is analyzed using mpn technique?

Mpn techinque (Most probable number) number of bacteria present in water sample ist of all we have a three set of tubes.in each set three three tubes are present,these set are for the probability,for this we taken the set of tubes,maximum nine tubes are taken.

sample serial dilution dones in all 9ml of lactose broth then we put the sample,

in ist tube we put 1 ml sample

in 2nd tube we put 1/10 ml

in 3rd we put 1/100 ml.

Now daram tube are put in tubes a s inverted,if enterobacteriacy member are present so the gas will produce and so daram tube move upward,b y this we chek the mpn.