The tables below show the hydrograph values for a region with three different zones. The first table gives the area enclosed within each zone. The zones are "nested" which means that Zone $1$ can be assumed to be in the middle, Zone $2$ surrounds Zone $1,$ and Zone $3$ surrounds Zones $2$ and $1($see picture$).$

a$.$ Given the data below, develop and plot the Maximum D$-$A$-$D curves for rainfall durations of $2-$hrs$,4-$hrs$,$ and $6-$hrs$.($Graph the DAD curves using: $1)$ linear$-$linear and $2)$ linear$-$log$)$

b$.$ For an county that has an area of $500$ square miles, what is the expected $($approximate$)$ depth of rainfall for a storm with a duration of $2hrs?$ What about for a storm with a duration of $5hrs?$

Enclosed Area Table:

$\backslash$table$[[$Time $($hrs$),$Zone $1,$Zone $2,$Zone $3],[$Enclosed Area $($sq$.$ mi$.),50,600,1400]]$

Hydrograph information. Rainfall depth in inches.

$\backslash$table$[[$Time $($hrs$),$Zone $1,$Zone $2,$Zone $3],[2,0\mathrm{.}59,0\mathrm{.}42,0\mathrm{.}32],[4,1\mathrm{.}44,0\mathrm{.}98,0\mathrm{.}71],[6,3\mathrm{.}94,1\mathrm{.}56,0\mathrm{.}95],[8,5\mathrm{.}21,2\mathrm{.}71,1\mathrm{.}31],[10,5\mathrm{.}73,3\mathrm{.}63,1\mathrm{.}55]]$