Total expenses of a boarding house are partly fixed and partly varying linearly with the number of boarders.The average expense per boarder is Rs. 700 when there are 25 boarders and Rs 600 when there are 50 boarders.What is the average expense per boarders when there are boarder ? Choose the most appropriate option:
A) 550
B) 580
C) 540
D) 570
E) None of these
Explanation :   Let x be the fixed cost and y the variable cost   17500 = x + 25y … (i)   30000 = x + 50y … (ii)   Solving the equation (i) and (ii), we get   x = 5000, y = 500   Now if the average expense of 100 boarders be ‘A’.   Then,   =&gt; 100 × A = 5000 + 500 × 100 .   ∴ A = 550.   550nswer : 550
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Total expenses of a boarding house are partly fixed and partly varying linearly with the number of boarders.The average expense per boarder is Rs. 700 when there are 25 boarders and Rs 600 when there are 50 boarders.What is the average expense per boarders when there are boarder ?