$10\mathrm{.}23$ Red Deer College promotes a wide variety of executive training courses for firms in the Red Deer area. Director Marilyn Helms believes that individually addressed letters add a personal touch to marketing. To prepare letters for mailing, she conducts a time study of her administrative assistants. On the basis of the observations shown in the following table, she wishes to develop a time standard for the whole job.

The college uses a total allowance factor of $12\%.$ Helms decides to delete all unusual observations from the time study. What is the standard time?

ElementObservations $($minutes$)$Performance Rating $(\%)123456$Typing letter$2\mathrm{.}53\mathrm{.}52\mathrm{.}82\mathrm{.}12\mathrm{.}63\mathrm{.}385$Typing envelope$0\mathrm{.}80\mathrm{.}80\mathrm{.}60\mathrm{.}83\mathrm{.}1$a$0\mathrm{.}7100$Stuffing envelope$0\mathrm{.}40\mathrm{.}51\mathrm{.}9$a$0\mathrm{.}30\mathrm{.}60\mathrm{.}595$Sealing, sorting$1\mathrm{.}02\mathrm{.}9$b$0\mathrm{.}91\mathrm{.}04\mathrm{.}4$b$0\mathrm{.}9125$