Question

ABC is a fast food joint serving three items: burgers, fries and ice cream. It has two employees Anish and Bani who prepare the items ordered by the clients. Preparation time is 10 minutes for a burger and 2 minutes for an order of ice cream. An employee can prepare only one of these items at a time. The fries are prepared in an automatic fryer which can prepare up to 3 portions of fries at a time, and takes 5 minutes irrespective of the number of portions. The fryer does not need an employee to constantly attend to it, and we can ignore the time taken by an employee to start and stop the fryer; thus, an employee can be engaged in preparing other items while the frying is on. However fries cannot be prepared in anticipation of future orders.
ABC wishes to serve the orders as early as possible. The individual items in any order are served as and when ready; however, the order is considered to be completely served only when all the items of that order are served. The information below gives the orders of three clients and the times at which they placed their orders:
1. client no 1 places order at 10.00 for 1 burger, 3 portion of fries and 1 order of ice cream.
2. client no. 2 places order at 10.05 for 2 portions of fries and 1 order of ice cream.
3. client no. 3 places order at 10.07 for 1 burger and 1 portion of fries.
\hrule Assume that only one client's order can be processed at any given point of time. So, Anish or Bani cannot start preparing a new order while a previous order is being prepared. At what time is the order placed by Client 1 completely served?

• A. 10.17
• B. 10.10
• C. 10.15
• D. 10.20

Hint:

To solve scheduling problems efficiently, identify the bottleneck task (the one that takes the longest time and cannot be split). Here, the burger takes 10 minutes, so the order cannot be completed in less than 10 minutes.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
To minimize the completion time of an order, tasks must be allocated to the two available employees (Anish and Bani) such that they work in parallel where possible.
We also utilize the automatic fryer's ability to run independently once started.
Detailed Explanation:
Let us analyze Client 1's order placed at 10:00:
- Items ordered: 1 burger, 3 portions of fries, 1 order of ice cream.
- Task durations:
1. Burger: 10 minutes (requires 1 employee).
2. Ice cream: 2 minutes (requires 1 employee).
3. Fries: 5 minutes in the automatic fryer (requires an employee only to start/stop the fryer, which takes negligible time).
Let us allocate the tasks at 10:00:
- Anish starts preparing the burger at 10:00. This task is completed at 10:10.
- Simultaneously, Bani starts the automatic fryer with 3 portions of fries at 10:00. These fries are ready at 10:05.
- Since the fryer operates automatically and does not require constant attention, Bani is free to immediately start preparing the ice cream at 10:00. The ice cream is ready at 10:02.
Now let us track the completion times of all components of Client 1's order:
- Ice cream is ready at 10:02.
- Fries are ready at 10:05.
- Burger is ready at 10:10.
An order is considered completely served only when all of its components are ready.
The last item (the burger) is completed at 10:10. Thus, the order is completely served at 10:10.

Step 2: Final Answer:
The order is completely served at 10:10, which corresponds to Option (B).