Which one the following relation is true about composite sleeper index (CSI)?
(S = General strength figure and H = General hardness figure)1
\(CSI = \frac{{S + 10H}}{{20}}\)
2
\(CSI = \frac{{H + 10S}}{{20}}\)
3
\(CSI = \frac{{S + 20H}}{{10}}\)
4
\(CSI = \frac{{S + 100H}}{{20}}\)