A process produces a product which requires to have a certain length. The capability ratio of this process is $1\mathrm{.}00,$ with a standard deviation of $1\mathrm{.}20.$ Determine the design tolerance of the product. $($Hint: if the designed tolerance of a product is $+/-0\mathrm{.}1,$ in this question you neeed to write just $0\mathrm{.}1$ as the answer$).$