Digit

[GmatKiss]

IMO: B

[Anurag@Gurome]

IMO: B

What is the tens digit of the positive integer r?

Let us assume that r = xyz, here tens digit is y.
We have to find the value of y.

(1) The tens digit of r/10 is 3.
r/10 = 3
r/10 = xy.z, which implies that tens digit here is x or x = 3, but there is no info about y; NOT sufficient.

(2) The hundreds digit of 10r is 6.
10r = xyz0, here hundreds digit is y, so y = 6; SUFFICIENT.

The correct answer is B.

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I got the answer as B. Just see the explanation...

Stimulus: What is the tens digit of the positive integer r?


Statement 1: The tens digit of r/10 is 3.

r/10 = H3U -------------> H stands for hundredth digit ; U stands for the Units Digit

Therefore, r = T3H0 ---------------> T stands for the thousands place ; Digit 3 turns to the hundredth digit ; H stands for the hundredth digit and 0 stands for the units digit.

So the hundredth place can vary from 0 to 9 as no information is given for that.

Hence statement 1 alone not sufficient.


Statement 2: The hundreds digit of 10r is 6.

10r = 6TU ------------------------> 6 is in the hundredth place ; T stands for the tenth place and U stands for the Units place.

We know that U has to be 0 because in the stimulus we are given that r is an integer.

so r = H6U ------------- where 0 will canceled out and the tens place will be taken by 6.

SO we know that 6 will be the tens place for the number r.

Hence statement 2 is sufficient.


Hence B is the correct answer...