#95 Average Quantitative Aptitude Question

There were 42 students in a hostel. If the number of students increases by 7, the expenses of the mess increases by Rs 49 per day.While the average expenditure per head diminishes by Rs. 1. Find the original expenditure of the mess. 

Solution : Let the average expenditure was Rs. x 

So total expenditure will be 42x. 
When 7 more students join the mess, total expenditure= 42x+49

 

   

So x= 14, therefore original expenditure of the mess= 42*14=Rs 588