Average of 10 two digit positive integer is Z. However, one number AB is taken as BA, then the average increases to Z+2.7. How many set of values for A and B are possible? Choose one: A) 5 B) 6 C) 7 D) 8 E) 9
Explanation :   Total such possible sets = (4,1), (5,2), (6,3), (7,4), (8,5) and (9,6).   (3,0) is not admissible as the numbers are of two digits.   Answer : 6
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Average of 10 two digit positive integer is Z. However, one number AB is taken as BA, then the average increases to Z+2.7. How many set of values for A and B are possible?