Harshit401 wrote:

Babita was to calculate the arithmetic mean of ten positive two digit integers. By miatake, she interchanged the two digits, say t & u, in one of these ten integers. As a result, her answer for arithmetic mean was 1.8 more than what it should have been. Then u-t equals

(A) 1

(B) 2

(C) 3

(D) 4

Hi Harshit401,

Let the interchanged integer 10t + u.

It is changed to 10u + t.

( 10u + t ) - ( 10t + u ) = 10 ( u - t ) + ( t - u ) = 9 ( u - t ) = 18

Then u - t = 2

The answer is B.

Happy Studying!

Math Revolution
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