$(20$ pts$)3.$ It is known for a region that observed relationship among observed intensity, duration and return periods can be defined by the expression $I=a\frac{T^b}{t^c}$ where I intensity, T return period, t is duration of the rainfall considered. $a,b$ and c are model parameters. Using the observation in Table $2$

x : The sum of last two digits of your student number

Table $2$: Rainfall intensities $(m\frac{m}{h})$

$\backslash$table$[[$Duration$/$Return periods,$T=5$ vears,$T=10$ vears,$T=20$ vears$],[2$ hr$,25+x,30+x,35+x$

x$=7$