A computer architecture student finds a recently published paper which says that, in the average MIPS system, $80\%$ of branches are taken.

Given the above information, what is the average CPI for only the branch instructions $($other instructions are not considered here$)$ for the design mentioned in Q$3\mathrm{.}2?[$hint: the CPI for an untaken branch is $1$; try to figure out the CPI for a taken branch.$]$

Exact Answer with error margin $0\mathrm{.}01$