A, B, and C can do a job in 18, 24, and 36 days, respectively. They work on alternate days in the order: Day 1 – C, Day 2 – B, Day 3 – A, Day 4 – C, and so on. In how many days will the work be finished?

Introduction / Context:
With alternating workers, compute the work done per full cycle and then scale up to cover the entire job. A 3-day cycle repeats until completion.

Given Data / Assumptions:

• A = 1/18, B = 1/24, C = 1/36 per day.
• Order: C, B, A, then repeats.

Concept / Approach:
Per 3-day cycle work = sum of daily rates in order. Divide 1 by the cycle sum to get number of cycles; multiply by 3 for days.

Step-by-Step Solution:

Verification / Alternative check:
Each cycle contributes exactly 1/8 of the job; 8 cycles complete it.

Why Other Options Are Wrong:
They do not match the exact cycle-sum fraction.

Common Pitfalls:
Adding times instead of rates or mis-ordering the pattern.

Final Answer:
24