$20\mathrm{.}27$ In computing state plane coordinates for a project area who's mean orthometric

height is $856\mathrm{.}47$ sft $,$ an average scale factor of $0\mathrm{.}99998347$ was used. The average

geoid height for the area is $-31\mathrm{.}284$ m $.$ The given distances between points in this

project area were computed from SPCS$83$ state plane coordinates. What horizon$-$

tal length would have to be observed to lay off these lines on the ground? $($Use

$6,371,000m$ for an average radius for the Earth.$)$

$($a$)*567\mathrm{.}79$ sft

$($b$)265\mathrm{.}054$ m

$($c$)2438\mathrm{.}25$ sft