Mr. Smith calculated the average of 10 three digit numbers. But due to a mistake he reversed the digits of a number and thus his average increased by 69.3. The difference between the unit digit and hundreds digit of that number is :  Choices.
A) 3	B) 4	C) 5	D) 6	E) 7
Since the average increased by 69.3 and there were a total of 10 numbers, it means the incorrect number was 693 greater than the correct number.   Say, the correct number was abc (where a, b and c are the digits of the 3 digit number)   Then the incorrect number was cba.   100c + 10b + a - (100a + 10b + c) = 693   99c - 99a = 99(c - a) = 693   693 = 99*7 = 99(c - a)   So c - a = 7   Answer (7)
<result>E</result>
Mr. Smith calculated the average of 10 three digit numbers. But due to a mistake he reversed the digits of a number and thus his average increased by 69.3. The difference between the unit digit and hundreds digit of that number is :