Task 1 -----

minutes
Task 2 ----- 3 min 10 sec = 3+10/60 =

minutes
Task 3 ----- 1 min
Total time to make 1 item =

+

+1 =

minutes
In 25 minutes;
Number of items made = 25/(6 2/3) = 3.75 items = 3 items (since only a fully assembly can be regarded as an item).