A hand assembly line with a takt time of 120 seconds consists of six operations with the following assembly times: Op1 is 60 sec, Op2 is 50 sec, Op3 is 40 sec, Op4 is 20 sec, Op5 is 65 sec and Op6 is 45 sec. To have a reasonably balanced line with some wait time, what should be the number of stations? And how many assemblers would be needed?