A direct time study was taken on a manual work element using the snapback method. The

regular cycle consisted of three elements, a$,$ b$,$ and c$.$ Element d is an irregular element

performed every five cycles.

Work element a b c d

Observed time $($min$)0\mathrm{.}560\mathrm{.}250\mathrm{.}501\mathrm{.}10$

Performance rating $100\%80\%110\%100\%$

Determine $($a$)$ normal time, $($b$)$ standard time for the cycle $($use PFD of $10\%),($c$)$ the average

performance of a worker if she produced $300$ units in an $8-$hour shift.