Mr. Smith calculated the average of 10three digit numbers. But due to a mistake he reversed the digits of a number and thus his average increased by 49.5. The difference between the unit digit and hundreds digit of that number is :
Select the correct option
A) 3
B) 4
C) 5
D) 6
E) 7
Since the average increased by 49.5 and there were a total of 10 numbers, it means the incorrect number was 49.5 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) = 495   99c - 99a = 99(c - a) = 495   495 = 99*5 = 99(c - a)   So c - a = 5   Answer (5)
<result>C</result>
Mr. Smith calculated the average of 10three digit numbers. But due to a mistake he reversed the digits of a number and thus his average increased by 49.5. The difference between the unit digit and hundreds digit of that number is :