c$)$ How many workstations are in your answer to $($b$)?$

The actual number of workstations used by Carlos in designing the assembly line for the istar phone $=6($enter your response as a whole number$).$

d$)$ What is the operating efficiency of your answer to $($b$)?$

The equation for the operating efficiency of a line balance follows:

Operating efficiency $=\frac{\text{T}\text{a}\text{s}\text{k}\text{t}\text{i}\text{m}\text{e}\text{s}}{(\text{N}\text{u}\text{m}\text{b}\text{e}\text{r}of\text{w}\text{o}\text{r}\text{k}\text{s}\text{t}\text{a}\text{t}\text{i}\text{o}\text{n}\text{s})(\text{L}\text{o}\text{n}\text{g}\text{e}\text{s}\text{t}\text{a}\text{s}\text{s}\text{i}\text{g}\text{n}\text{e}\text{d}\text{t}\text{a}\text{s}\text{k}\text{t}\text{i}\text{m}\text{e})}.$

The task time is equal to the longest operation time of all of the workstations, which is ${57}^7$ seconds $($enter your response as a whole number$).$

The operating efficiency of the assembly line $=,\%($enter your response as a percentage rounded to two decimal places$).$