Automan, Inc The Desired Output Rate Is 50 Robots an Hour

Multiple Choice

Automan, Inc. makes "tennis robots" on an assembly line with 9 tasks. The tasks and their times follow. $$\begin{array} { | l | l | } \hline \text { Work } & \text { Time } \\\text { Element } & ( \mathrm { sec } ) \\\hline 1 & 20 \\\hline 2 & 30 \\3 & 25 \\4 & 25 \\5 & 10 \\6 & 20 \\7 & 15 \\8 & 45 \\9 & 50 \\\hline\end{array}$$ The desired output rate is 50 robots an hour. The "theoretical maximum efficiency" on the line is

A) less than 85%.
B) more than 85% but less than or equal to 90%.
C) more than 90% but less than or equal to 95%.
D) more than 95%.