If the ratio of lengths, radii and Young’s moduli of steel and brass wires in the figure are $a, b$ and $c$ respectively. Then the corresponding ratio of increase in their lengths would be:

 

If a rubber ball is taken at the depth of $200 \text{m}$ in a pool, its volume decreases by $0.1\%$. If the density of the water is $1\times {10}^3 \mathrm{kg} {\mathrm{m}}^{-3}$ and $g=10 \mathrm{m} {\mathrm{s}}^{-2}$, then the volume elasticity in $\mathrm{N} {\mathrm{m}}^{-2}$ will be