An assembly line consists of 21 tasks grouped into 5 workstations. The sum of the 21 task durations is 75 minutes. Cycle time for the line is 20 minutes. The efficiency of this line is:
75 percent
81 percent
85 percent
100 percent
none of these
The correct answer and explanation is :
To calculate the efficiency of the assembly line, we need to use the formula for line efficiency:
[
\text{Efficiency} = \frac{\text{Total Task Time}}{\text{Number of Workstations} \times \text{Cycle Time}} \times 100
]
Step 1: Identify the given data:
- Total task time (sum of task durations) = 75 minutes
- Number of workstations = 5
- Cycle time = 20 minutes
Step 2: Calculate the theoretical minimum time required for the line.
The theoretical minimum time required for the line is determined by the formula:
[
\text{Theoretical minimum time} = \text{Number of Workstations} \times \text{Cycle Time}
]
Substituting the given values:
[
\text{Theoretical minimum time} = 5 \times 20 = 100 \text{ minutes}
]
Step 3: Calculate the line efficiency.
Now, we use the efficiency formula to find the percentage efficiency:
[
\text{Efficiency} = \frac{75 \text{ minutes}}{100 \text{ minutes}} \times 100 = 75\%
]
Step 4: Interpret the result.
The efficiency of the assembly line is calculated as 75%. This means that the line is operating at 75% efficiency, using 75 minutes of total task time for a theoretical minimum of 100 minutes, given the 5 workstations and the 20-minute cycle time.
Conclusion:
The correct answer is 75 percent.
The line efficiency is an important metric as it measures how effectively the assembly line is utilizing the available time. A higher efficiency indicates better performance and less wasted time. In this case, the assembly line has an efficiency of 75%, meaning 25% of the time is being spent on inefficiencies, such as downtime, delays, or idle time at workstations.