BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Number System

Expert replies
by adthedaddy » Thu Sep 24, 2015 7:29 pm
If q is positive two-digit integer and p is the units digit of q, is 10<q<50 ?

1. p is more than the tens digit of q.
2. 4p-1 = q

Standard DS options follow
"Your time is limited, so don't waste it living someone else's life. Don't be trapped by dogma - which is living with the results of other people's thinking. Don't let the noise of others' opinions drown out your own inner voice. And most important, have the courage to follow your heart and intuition. They somehow already know what you truly want to become. Everything else is secondary" - Steve Jobs
Join the discussion
Source: — Data Sufficiency |

by swa_mac » Thu Sep 24, 2015 9:35 pm
IMO: B

1. Insufficient: since the number can be 12 or 89 or 56; Since the units digit is larger than the Units digit.
2. Sufficient: 4p-1= q; given
but we know that q= 10x+p
hence equating two, we have; 4p-1=10x+p; p= {10x+1}/3;
hence q= {40x+1}/3 and X can take values from 1 till 9
Hence substituting 1 we have 41 which is not divisible by 3
Substituting 2 we have 81; then q= 27 and we cannot substitute 3 inplace of x as it leads to a 3 digit number.

Hence, B is the sufficient.
Join the discussion

by Matt@VeritasPrep » Fri Sep 25, 2015 12:49 am
S1: Not sufficient, we could have 47 or 89 or many other things.

S2: q + 1 = 4p, so (q + 1) is a multiple of 4. Since p is a single digit integer and q is a two-digit integer, we could have p = 3, 4, 5, ..., 9, and hence q = 11, 15, ..., 35. So whatever q is, it must be between 11 and 35, inclusive; SUFFICIENT.
Join the discussion