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 19.8. The difference between the unit digit and hundreds digit of that number is : Choose the correct option.
A) a) 4 B) b) 3 C) c) 2 D) d) 1 E) e) 0
Since the average increased by 19.8 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   Answer (c) 2)
<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 19.8. The difference between the unit digit and hundreds digit of that number is :