Question 1105416
(0-4) (4-6) (6-10) (10-16) (16-18) Total
20 | 50 | 100   | 120   | 110 |   400
middle range is 2*20+5*50+8*100+13*120+17*110
This is 40+250+800+1560+1870=4520
divide by 400
average age is 11.3
With the age distribution 16 and older, the conservative way is to use the 110 in the group or 16,500 Rs.
This misses some of the age group 10-16, which could be changed by having the groups either include the top number or not include it.  If included, those 16 and older wouldn't be counted.  If not, those who were 16 would be counted in the oldest group.  The 5 and under would be 70*500=35,000 Rs.  This would take the whole group, even 6 year-olds but is fair as the average is counted.  

One just has to realize that the middle of the second group sets the average and the whole group is then considered 5 and under.  The oldest group is probably better left alone with none from the second highest.

The total I would calculate is 51,500 Rs.