Indian Institute of Foreign Trade 2012 Solved Paper

Let the total fees = T, the fixed fees = F, the number of students = n and let x be the varying fees.
Thus, T = F + nx
Given, when n = 20, T = 8000
Thus, 8000 = F + 20x
Also, when n = 40, T = 12000
Thus, 12000 = F + 40x
Solving we get F = 4000 and x = 200
Thus, the average rent when 80 students are staying =

4000

80

+200=250Rs
Hence, option A is the correct answer.