Four identical hollow cylindrical column of steel support a big structure of mass $50000\;kg$. The inner and outer radii of each column are 30 and 60 cm respectively. Assuming load distribution to be uniform , the compressional strain of each column is $[y_{steel}=2.0 \times 10^{11} Nm^{-2}]$

Question

$$\begin {array} {1 1} (a)\;7.2 \times 10^{-7} \\ (b)\;15.2 \times 10^{-7} \\ (c)\;8.4 \times 10^{-7} \\ (d)\;12.1 \times 10^{-7} \end {array}$$