Physics - Modern Physics Question with Solution | TestHub

Half-life, $T=1600$ years Time of decay, $t=6400$ years Number of half-lives, $n=\frac{t}{T}=\frac{6400}{1600}=4$ Fraction undecayed $=\frac{N}{N_0}={\left(\frac{1}{2}\right)}^n={\left(\frac{1}{2}\right)}^4=\frac{1}{16}$