An initial time study was done on a process with the following results $($in minutes$).$ Based on the data obtained so far, assuming an allowance of $1111$ percent of the normal time, what do you estimate for the time per customer served, based on this preliminary sample? $($Round all intermediate calculations to two decimal places.$)$ ElementPerformanceRatingObs$1$Obs$2$Obs$3$Obs$4$Obs$5$Element $180803355443355$Element $29090111110101111101088$Element $31301306666776666$ Part $2$The time per unit customer served is enter your response here minutes. $($Enter your response rounded to two decimal places.$)$