Ashishmathew01081987 wrote:

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 29.7. The difference between the unit digit and hundreds digit of that number is :

a) 4

b) 3

c) 2

d) 1

e) 0

Since the average increased by 29.7 and there were a total of 10 numbers, it means the incorrect number was 297 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) = 297

99c - 99a = 99(c - a) = 297

297 = 99*3 = 99(c - a)

So c - a = 3

Answer (B)

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