Hemo$-$tech, Inc., a biomedical technology and research laboratory, produces a standard blood filtering device on an assembly$-$line basis. Six basic tasks are performed along the assembly line. The time to perform each task and the tasks that must immediately precede each task are in the table below. Twenty pumps per $450-$minutes day must be produced by the assembly line.

Task

Preceding Task

Time to perform $($min$)$

A

$--$

$5\mathrm{.}4$

B

A

$3\mathrm{.}2$

C

$--$

$1\mathrm{.}5$

D

B$,$ C

$2\mathrm{.}8$

E

D

$17\mathrm{.}1$

F

E

$12\mathrm{.}8$