for the time per customer served, based on this preliminary sample? $($Round all intermediate calculations to two decimal places.$)$

$\backslash$table$[[,$Performance,Obs,Obs,Obs,Obs,Obs$],[$Element$,$Rating,$1,2,3,4,5],[$Element $1,80,4,4,3,5,6],[$Element $2,90,11,10,10,8,9],[$Element $3,130,6,6,7,7,8]]$

The time per unit customer served is

minutes. $($Enter your response rounded to two decimal places.$)$