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

Redeem

A={x|(7/15)x+1/3 = 4/3} and B={y| 2m-(1/15)y = 3}, where m i

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members

A={x|(7/15)x+1/3 = 4/3} and B={y| 2m-(1/15)y = 3}, where m i

by Max@Math Revolution » Wed Aug 21, 2019 12:11 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

[GMAT math practice question]

A={x|(7/15)x+1/3 = 4/3} and B={y| 2m-(1/15)y = 3}, where m is a real number. What is the value of m?

1) A ∩ B ≠ Ø
2) B ≠ Ø
Top
Source: — Data Sufficiency |
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members

by Max@Math Revolution » Fri Aug 23, 2019 12:25 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

=>

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

The first step of the VA (Variable Approach) method is to modify the original condition and the question. We then recheck the question. We should simplify conditions if necessary.

Since (7/15)x+1/3 = 4/3 and 7x + 5 = 20 by definition of set A, we must have x = 15/7 and A = { 15/7 }.
Since 2m-(1/15)x = 3 and 30m - x = 45 by definition of set B, x = 30m - 45 and B = { 30m - 45 }.

Since we have 1 variable (m) and 0 equations, D is most likely to be the answer. So, we should consider each condition on its own first.

Condition 1)
Since A ∩ B ≠ Ø, we must have 30m - 45 = 15/7 and condition 1) yields a unique solution. It is sufficient.

Condition 2)
Since m can be any value and condition 2) doesn't yield a unique solution, it is not sufficient.

Therefore, A is the answer.
Answer: A

If the original condition includes "1 variable", or "2 variables and 1 equation", or "3 variables and 2 equations" etc., one more equation is required to answer the question. If each of conditions 1) and 2) provide an additional equation, there is a 59% chance that D is the answer, a 38% chance that A or B is the answer, and a 3% chance that the answer is C or E. Thus, answer D (conditions 1) and 2), when applied separately, are sufficient to answer the question) is most likely, but there may be cases where the answer is A,B,C or E.
Top
Post new topic Post Reply
• Page 1 of 1