What is the formula for the relative stability of treated sewage?
[t20 : Time taken by a sample of seabease to bleach in a standard volume of methylene blue solution at 20°C, (in days)]:
1
\(S=100\left[1-0.630^{t_{20}}\right]\)
2
\(S=100\left[1-0.543^{t_{20}}\right]\)
3
\(S=100\left[1-0.794^{t_{20}}\right]\)
4
\(S=100\left[1-0.116^{t_{20}}\right]\)