If the units digit of the three-digit positive integer k is nonzero, what is the tens digit of k?
(1) The tens digit of k + 9 is 3.
(2) The tens digit of k + 4 is 2.
Good Numbers/Digits Question
This topic has expert replies
-
- Senior | Next Rank: 100 Posts
- Posts: 44
- Joined: Tue Mar 05, 2013 10:18 pm
- Thanked: 4 times
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
Target question: What is the tens digit of k?rishianand7 wrote:If the units digit of the three-digit positive integer k is nonzero, what is the tens digit of k?
(1) The tens digit of k + 9 is 3.
(2) The tens digit of k + 4 is 2.
Statement 1: The tens digit of k + 9 is 3
If the units digit of k is not zero, then it must be 1 or 2 or . . .or 8 or 9
So, when we add 9 to k, the tens digit must increase by one.
So, if the tens digit of k + 9 is 3, then the tens digit of k must be 2
Since we can answer the target question with certainty, statement 1 is SUFFICIENT
Statement 2: The tens digit of k + 4 is 2
Consider these two possible values of k:
Case a: k = 17, since the tens digit of k + 4 (aka 21) is 2. In this case, the tens digit of k is 1
Case b: k = 23, since the tens digit of k + 4 (aka 27) is 2. In this case, the tens digit of k is 2
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT
Answer = A
Cheers,
Brent
Last edited by Brent@GMATPrepNow on Tue Aug 06, 2013 7:29 am, edited 2 times in total.
-
- Senior | Next Rank: 100 Posts
- Posts: 44
- Joined: Tue Mar 05, 2013 10:18 pm
- Thanked: 4 times
Hey Brent,
The OA is A.
The question states that "the units digit of the three-digit positive integer k is nonzero". Hence 'k' cannot be 30.
Thanks for the solution, I was able to deduce the answer using your explanation.
Regards,
Rishi
The OA is A.
The question states that "the units digit of the three-digit positive integer k is nonzero". Hence 'k' cannot be 30.
Thanks for the solution, I was able to deduce the answer using your explanation.
Regards,
Rishi
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
Hi Rishi,
You're absolutely right. Lazy mistake on my part to miss that crucial piece of information.
I have edited my response accordingly.
Thanks and cheers,
Brent
You're absolutely right. Lazy mistake on my part to miss that crucial piece of information.
I have edited my response accordingly.
Thanks and cheers,
Brent