Final answer:
The lunch hour cycle time is 2 hours.
Step-by-step explanation:
To calculate the lunch hour cycle time, we need to divide the total number of customers by the number of customers you can assist per hour.
Given that you can assist 10 customers per hour, and 20 customers entered the store during the lunch hour, the cycle time would be:
Cycle time = Total number of customers / Number of customers you can assist per hour
Cycle time = 20 customers / 10 customers per hour = 2 hours
Therefore, your lunch hour cycle time is 2 hours.