65292 

As per given conditions, there are three possible 
combinations for 2nd, 3rd and 4th digits. They are (3, 0, 
7) or (4, 1, 8) or (5, 2, 9) 

It is given that there are 3 pairs whose sum is 11. All 
possible pairs are (2, 9), (3, 8), (4, 7), (5, 6). Now 
required number is 5 digit number and it contains 3 pairs 
of 11. So it must not be having 0 and 1 in it. Hence, the 
only possible combination for 2nd, 3rd and 4th digits is 
(5, 2, 9) 

Also, 1st digit is thrice the last digit. The possible 
combinations are (3, 1), (6, 2) and (9, 3), out of which 
only (6, 2) with (5, 2, 9) gives 3 pairs of 11. Hence, the 
answer is 65292.