Double Wipe
A clean piece of cloth is sprayed with a certain disinfectant liquid, and applied to (rubbed on) a surface that is known to contain germs. After the first wipe, a second piece of cloth identical to the first is sprayed with the same amount of the disinfectant liquid, and applied again in the same way to the surface. If a single wipe of the surface is estimated to kill of the germs, what is the expected percentage of germs (relative to the original number of germs) that will be killed by this double wipe procedure. Take .
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1 solution
expected percentage of germs (relative to the original number of germs) that will be killed by this double wipe procedure
= 1 – (1 – 98%)^(number of wipes)
= 1 – (0.02)²
= 0.9996
= 99.96%