Events & Promotions
|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Nov 2007:30 AM PST
-08:30 AM PST
Learn what truly sets the UC Riverside MBA apart and how it helps in your professional growth
Nov 2211:00 AM IST
-01:00 PM IST
Do RC/MSR passages scare you? e-GMAT is conducting a masterclass to help you learn – Learn effective reading strategies Tackle difficult RC & MSR with confidence Excel in timed test environment- Nov 23
11:00 AM IST
-01:00 PM IST
Attend this free GMAT Algebra Webinar and learn how to master the most challenging Inequalities and Absolute Value problems with ease. 
Nov 2510:00 AM EST
-11:00 AM EST
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors.
11 Jun 2018, 02:35
Kudos
Bookmarks
A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
75% (01:21) correct
25%
(02:09)
wrong
based on 32
sessions
History
Date
Time
Result
Not Attempted Yet
Working alone at its constant rate, machine A can produce 240 pins in \(x\) hours. Working alone at its constant rate, machine B can produce 240 pins in \(y\) hours. How many hours will it take machines A and B to produce 240 pins, when working together at their respective constant rates?
1) \(xy/(x+y)=4\)
2) \(x=20\)
1) \(xy/(x+y)=4\)
2) \(x=20\)
11 Jun 2018, 02:35
Kudos
Bookmarks
Official Solution:
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, and then recheck the question.
We have \(1/t = 1/x + 1/y = (x+y)/xy\) or \(t = xy/(x+y)\), where t is the time that machines A and B take to produce 240 pins, when working together. The question asks for \(xy / (x+y)\).
Thus, only condition 1) is sufficient. Condition 2) is not sufficient as it only gives us information about \(x\).
Therefore, the answer is A.
Answer: A
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, and then recheck the question.
We have \(1/t = 1/x + 1/y = (x+y)/xy\) or \(t = xy/(x+y)\), where t is the time that machines A and B take to produce 240 pins, when working together. The question asks for \(xy / (x+y)\).
Thus, only condition 1) is sufficient. Condition 2) is not sufficient as it only gives us information about \(x\).
Therefore, the answer is A.
Answer: A
