Answer:
6 days
Explanation:
We are given that
Half life,[tex]t=2 days[/tex]
We have to find the time must elapse before the room is safe to enter.
Let maximum permissible level=[tex]N_0[/tex]
Radiation,[tex]N=8N_0[/tex]
Let n be the number of half cycle
[tex]\frac{N}{N_0}=2^n[/tex]
[tex]\frac{8N_0}{N_0}=2^n[/tex]
[tex]8=2^n[/tex]
[tex]2^3=2^n[/tex]
[tex]n=3[/tex]
Time must elapse before the room is safe to enter=[tex]3t=3\times 2=6days[/tex]
