Tricky DS problem

[poonamchiK]

If n is a positive integer, what is the tens digit of n?
1. The hundreds digit of 10n is 6
2. The tens digit of n+1 is 7.

answer is (b)

I dnt know why!

[ronaldramlan]

If n is a positive integer, what is the tens digit of n?
1. The hundreds digit of 10n is 6
2. The tens digit of n+1 is 7.

answer is (b)

I dnt know why!

Hmmm ... I can understand your confusion. Statement 2 should be insufficient. We can use "picking number" to make a test case. If we consider n=70, the tens digit of n+1 will be the same as that of n. However, if n=69, the tens digit of n+1 will have a different result from that of n.
In my opinion, statement 1 should be sufficient. Therefore, the answer should have been A.

[Ben Ku]

Please cite the source (author) of this problem. We cannot reply unless a source is cited (and, if no source is cited, we will have to delete the post!). Thanks.

[poonamchiK]

Hey Ben,
question is from OG is suppose. my centre prepares tests solely from OG.

Poonam

[ps63739]

I believe answer should be A.
2nd option can lead to either 6 or 7.

[michael_shaunn]

I am with ps63739.The answer should be A.