In: Civil Engineering
As stated in the question:
Total Formwork = 5000 SFCA
Rate of building and erecting = 5 man-hours. (It is understood that it per unit of work )
Therefore,
Total duration required will be = 5000/5
= 1000 man hours.
Now, understanding from the question that the rate of building and erection applies to the capacity of skilled labour i.e in our case the carpenter. Therefore from the given data, it can be safely stated that if only one carpenter worked, it would consume 1000 man-hours for completion of given work.
However, in the given case the 4 carpenters are assisted by 2 labours as well. Since the construction duration also includes unskilled tasks like loading, unloading etc, which can be assisted by the labours, we can safely assume that that the rate of labours will be 50% of that of the carpenter. Or in other words, the labours will enhance the efficiency/rate of the carpenter.
Therefore number of workers= 4 (Carpenter)+ 2* 50% efficiency ( Labours)
= 5 Workers
Therefore Total duration required = 1000/5
= 200 man hours
Solution: 4 Carpenters and 2 labours can together complete the work in 200 man hours.