If the mean of the data is 8.1 and ${\displaystyle \sum f_i{x}_i}=132+5k,{\displaystyle \sum f_i=20}$ , then $k=$

${\displaystyle \sum fixi}=132+5k$

${\displaystyle \sum fi=20}$

Mean $=\frac{{\displaystyle \sum fixi}}{{\displaystyle \sum fi}}$

$\Rightarrow 8.1=\frac{132+5k}{20}$

$\Rightarrow 162=132+5k$

$\Rightarrow 5k=162-132$

$\Rightarrow k=6$