The number of circular divisions on the shown screw gauge is $50$. It moves $0.5 \mathrm{mm}$ on main scale for one complete rotation. Main scale reading is $2$. The diameter of the ball is:

 

There are two Vernier calipers both of which have $1 \mathrm{cm}$ divided into $10$ equal divisions on the main scale. The Vernier scale of one of the calipers $\left({\mathrm{C}}_1\right)$ has $10$ equal divisions that correspond to $9$ main scale divisions. The Vernier scale of the other caliper $\left({\mathrm{C}}_2\right)$ has $10$ equal divisions that correspond to $11$ main scale divisions. The readings of the two calipers are shown in the figure. The measured values (in $\mathrm{cm}$) by calipers ${\mathrm{C}}_1$ and ${\mathrm{C}}_2$, respectively, are