Radiactive element due to accident in research laboratory gets embedded in its floor and walls. The initial rate of decay is 64 times the safe limit. The half life of the element is 32 days. Calculate the time after which the laboratory will be safe for use.

Explanation

`N_(0) = 64 N`
`(0.693)/(t_(1//2)) = (2.303)/(t) log_(10) (N_(0))/(N)`
`(0.693)/(32) = (2.303)/(t) log_(10) [(64 N)/(N)]`
t = 192 days