An electronics manufacturer makes remote control devices for interactive$-$cable$-$TV systems. The following assembly tasks must be performed on each device.

Task

Description

Predecessor$($s$)$

Time $($min$.)$

A

Place circuit into circuit frame

$--$

$0\mathrm{.}50$

B

Solder circuit connections to central circuit control

A

$0\mathrm{.}70$

C

Place circuit assembly in device frame

B

$0\mathrm{.}40$

D

Attach circuit assembly to device frame

C

$0\mathrm{.}30$

E

Place and attach display to frame

$--$

$0\mathrm{.}30$

F

Place and attach keypad to frame

$--$

$0\mathrm{.}20$

G

Place and attach top body of device to frame

E$,$ F

$0\mathrm{.}35$

H

Place and attach battery holder to frame

D

$0\mathrm{.}40$

I

Place and attach bottom body of device to frame

G$,$ H

$0\mathrm{.}60$

J

Test device

I

$0\mathrm{.}30$

Draw the precedence diagram for this problem, then determine the following:

a$.$ What is the sum of the task times?