The Production of a Product Consists of Seven Work Elements

Multiple Choice

The production of a product consists of seven work elements. The desired output rate is 2 units per minute. The work elements and their precedence relationships follow. $$\begin{array} { | c | l | l | } \hline \begin{array} { c } \text { Work } \\\text { Element }\end{array} & \text { Time (sec) } & \begin{array} { l } \text { Immediate } \\\text { Predecessor(s) }\end{array} \\\hline 1 & 15 & - \\2 & 16 & 1 \\3 & 12 & 2 \\4 & 14 & 3 \\5 & 18 & 2,4 \\6 & 12 & 5 \\7 & 20 & 4 \\\hline\end{array}$$ Using the longest work- element time method, how many stations are required?

A) 2 stations
B) 3 stations
C) 4 stations
D) 5 stations