original $6\mathrm{.}20b$

Specifications are $6\mathrm{.}40+-0\mathrm{.}15mm$ and

the population standard deviation of the process is $0\mathrm{.}030($After improvement value$)$

And the process is centered at $6\mathrm{.}30,$

What is the Cpk$?$

Answer with two decimal precision $($#$,$##$)$