$7\mathrm{.}31$ The constant$-$head permeameter shown in Figure $7\mathrm{.}25$ contains three different soils shown. Their hydraulic conductivites are as follows:

Soil $1-k=9c\frac{m}{s}$

Soil $2-k=6{10}^{-2}c\frac{m}{s}$

Soil $3-k=8{10}^{-3}c\frac{m}{s}$

The four piezometer tips are spaced at $100mm$ intervals, and the soil interface are exactly aligned with piezometer tips $B$ and $C.$ The total heads given by piezometers and D are $98\mathrm{.}9$ and $3\mathrm{.}6cm,$ respectively. Compute the total heads given by piezometers $B$ and $C.$