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.
Target question:
What is the tens digit of k?
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
