The correct choice is (b) 93.33 sq m.
The explanation is: Average pay = 400+1000/2 = Rs. 700.00 per month.
Average monthly rent @ 10% of salary = 700.00/10 = Rs.70.00
Average annual rent 70.0*12 = Rs.840.00.
Capital cost of the building @ 6%interest = 840*100/6 = Rs.14000.00
Plinth area required @Rs.150.00 per sq m of plinth area = 14000/150 = 93.33 sq m.
Normally the quarter for the assistant engineer should be constructed at the cost of Rs.14000.00 having plinth area of 93.33 sq m.
But due to the increase in the cost of construction, this may be increased by 100% and the capital cost of construction may be fixed as Rs.2800.00 and the approximate plinth area of 93.33.