A certain disinfectant has a decimal reduction time of 100 s

A certain disinfectant has a decimal reduction time of 100 seconds. When used to completely disinfect a surface conatining 1 x 10^6 bacterial cells, how long must the surface be soaked in the disinfectant?

Solution

Decimal reduction time = 100 sec

disinfectant surface = 1 x 10 ⁶ bacterial cells

surface is soaked in disinfectant = 1x10 ⁶ bacterial cells / 10 ³

                                                     = 1 x 10 ³