This is a super fun question!
Say,
Work done by Shyam in a day = x
Then,
Work done by Ram in a day = 1.5x or (3/2)x (Because Ram is 50% more efficient)
Both can together complete a work in 24 days.
Work = (1.5x+x)24 = 60x
Both start working together. Ram takes rest every 2nd day and Shyam every 3rd day. On which day will the work get completed?
One can also take a set of example numbers.
Say -> x = 2 (Shyam); 1.5x = 3 (Ram); 60x = 120 (Work done).I started looking for a scalable pattern which I could use.

If we observe the pattern of work done, we can see that
- Every 6 days, 8.5x units of work gets done.
- What is the closest we can get to 60x in terms of 6-day sets? 8.5x * 7 = 59.5x.
- What this means is that by 6*7 = 42 days, 59.5x units out of 60x units of work will get done.
- Hence, the work will get done by the 43rd day. Choice D.
If we use the example numbers from above,
- Every 6 days, 17 units of work get done.
- The closest we can get to 120 in terms of 6-day sets? 17*7 = 119.
- This means that by 6*7 = 42 days, 119 out of 120 units of work will get done.
- hence, the work will get done by the 43rd day. Choice D.
Hope this helps.
___
Harsha
Passionate about all things GMAT | Exploring the GMAT space | My website: gmatanchor.com
Attachment:
GMAT-Club-Forum-r9o4sq4p.png [ 169.29 KiB | Viewed 814 times ]