Walkabout wrote:
Is the positive two-digit integer N less than 40 ?
(1) The units digit of N is 6 more than the tens digit.
(2) N is 4 less than 4 times the units digit.
Target question: Is N less than 40 Given: N is a positive two-digit integer
Statement 1: The units digit of N is 6 more than the tens digitThis statement is, essentially, restricting the value of the tens digit.
If the units digit is 6 more than the tens digit, then the tens digit cannot be very big.
For example, the tens digit cannot be 8, because the units digit would have to be 14, which is impossible.
Likewise, the tens digit cannot be 4, because the units digit would have to be 10, which is also impossible.
So,
the greatest possible value of the tens digit of N is 3.
As such,
N must be less than 40Since we can answer the
target question with certainty, statement 1 is SUFFICIENT
Statement 2: N is 4 less than 4 times the units digit. Well, 9 is the greatest possible value of a digit, and if the units digit were 9, then N would equal (4)(9) - 4, which is less than 40
So, no matter what value the units digit has, the resulting number (N),
must be less than 40Since we can answer the
target question with certainty, statement 2 is SUFFICIENT
Answer: DCheers,
Brent