The trade magazine QSR routinely checks the drive-through service times of fast-food restaurants. A 80% confidence interval that results from examining 541 customers in Taco Bell's drive- through has a lower bound of 166.9 seconds and an upper bound of 172.7 seconds. Complete parts (a) through (C). (a) What is the mean service time from the 541 customers? The mean service time from the 541 customers is seconds (Type an integer or a decimal. Do not round.) (b) What is the margin of error for the confidence interval? The margin of error is seconds