$9.$ BM A $=100\mathrm{.}000$ BM B $=100\mathrm{.}000$ BM C $=100\mathrm{.}000$

from station to station elev. diff. error est.

BM A $1+\mathrm{.}02\mathrm{.}01$

BM B $1-\mathrm{.}01\mathrm{.}02$

BM C $1+\mathrm{.}01\mathrm{.}03$

Using a matrix solution compute the $95\%$ confidence standard deviation in

the elevation of $1.$

$10.$ Double all of the error estimates in $9-11.$ and recompute using a

matrix solution the $95\%$ confidence standard deviation in the elevation

of $1.$