OSPE

House Index = no of positive houses/ no of houses visited x 100 

     = 10/100 x 100 = 10 (High density)

Container Index = no of positive containers / no of containers examined x 100 

     = 50/200 x 100 = 25   (High density)

Breteaux Index = no. of positive containers x 100

                           Total no. of houses visited

=    50 x 100=50 (High density)

     100