The concentric spherical conducting shells are arranged in vacume as shown in fig. the electric capacity of the arrangement between ‘A’ and ‘B’ will be _______ times of ${\mathrm{\pi \epsilon }}_0\mathrm{A}$

C of inner and middle shell $=\frac{4{\mathrm{\pi \epsilon }}_0\mathrm{q}\times 2\mathrm{q}}{2\mathrm{q}-\mathrm{q}}$

C of midde and outer shell$=\frac{4{\mathrm{\pi \epsilon }}_0\left(2\mathrm{q}\right)\left(3\mathrm{q}\right)}{3\mathrm{q}-2\mathrm{q}}$

capacity of outer shell $=4{\mathrm{\pi \epsilon }}_0\left(3\mathrm{q}\right)$ = outer surface of outer shell also have some charge because it is not earthed. 

Hence its capacity is also to be considered.