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 19.8 The difference between the unit digit and hundreds digit of that number is :
Choose the most appropriate option.
A) 2
B) 6
C) 5
D) 3
E) 4
Since the average increased by 29.7 and there were a total of 10 numbers, it means the incorrect number was 198 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) = 198   99c - 99a = 99(c - a) = 198   198 = 99*2 = 99(c - a)   So c - a = 2   2nswer (2)
<result>A</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 19.8 The difference between the unit digit and hundreds digit of that number is :