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.
Jul 1206:30 AM PDT
-08:30 AM PDT
Join our webinar to master GMAT RC Main Point Questions! Learn effective strategies to decipher passage themes and purposes. Senior Verbal Expert- Sunita Singhvi will equip you with tools to navigate complexities and avoid common traps set by the GMAT.
Jun 3008:00 AM PDT
-11:59 PM PDT
Join us June 30th for 2 weeks of GMAT questions (just 8 per day) to help with your prep and to compete with your fellow GMAT Clubbers for a chance to win a prize fund of $30,000 for you and your team-mates!
Jul 0901:00 PM EDT
-02:00 PM EDT
More Target Test Prep students are earning 100th percentile GMAT scores. Don’t settle for less when the Target Test Prep course gives you everything you need to score high on the GMAT. Start your 5-day free trial today.
Jul 1211:00 AM IST
-01:00 PM IST
Attend this session to learn how to Deconstruct arguments, Pre-Think Author’s Assumptions, and apply Negation Test.
Jul 1311:00 AM EDT
-12:30 PM EDT
Looking for your GMAT motivation to break through the score plateau? Pragati improved her score by massive 160 points with strategic guidance and hard-work! Find out how personalized mentorship and a strong mindset can turn GMAT struggles into success.
Jul 1508:00 PM PDT
-09:00 PM PDT
Full-length FE mock with insightful analytics, weakness diagnosis, and video explanations!
Jul 1611:00 AM EDT
-12:00 PM EDT
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.
16 Sep 2014, 00:12
Kudos
Bookmarks
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
75%
(hard)
Question Stats:
48% (01:55) correct
52%
(02:05)
wrong
based on 380
sessions
History
Date
Time
Result
Not Attempted Yet
List A consists of 10 terms, each of which is a reciprocal of a prime number, is the median of the list less than 1/5?
(1) The reciprocal of the median of the list is a prime number.
(2) The product of any two terms of the list is a terminating decimal.
(1) The reciprocal of the median of the list is a prime number.
(2) The product of any two terms of the list is a terminating decimal.
16 Sep 2014, 00:12
Kudos
Bookmarks
Official Solution:
List A consists of 10 terms, each of which is a reciprocal of a prime number, is the median of the list less than 1/5?
(1) The reciprocal of the median is a prime number.
If all the terms in the list are 1/2, then the median is 1/2, which is not less than 1/5. On the other hand, if all the terms are 1/7, then the median is 1/7, which is less than 1/5. Not sufficient.
(2) The product of any two terms of the list is a terminating decimal.
Since the terms in the list are reciprocals of prime numbers, the product of any two terms will be a reduced fraction \(\frac{1}{p*q}\), where \(p\) and \(q\) are prime numbers. For a reduced fraction, in its decimal form, to have a finite number of digits after the decimal point, it must have only 2's and/or 5's in its denominator. Therefore, the list can only consist of 1/2's, 1/5's, or a combination of 1/2's and 1/5's. It cannot include the reciprocal of any other prime, such as 1/3, because no pair with 1/3 will produce a product that is a terminating decimal.
If the two middle terms are both 1/2, then the median is 1/2, which is NOT less than 1/5.
If the two middle terms are both 1/5, then the median is 1/5, which is NOT less than 1/5.
Finally, if the two middle terms are 1/5 and 1/2, then the median is (1/5 + 1/2)/2 = 7/20, which is also NOT less than 1/5.
Since none of the possible medians are less than 1/5, the answer to the question is no. Therefore, statement (2) alone is sufficient to answer the question.
Answer: B
List A consists of 10 terms, each of which is a reciprocal of a prime number, is the median of the list less than 1/5?
(1) The reciprocal of the median is a prime number.
If all the terms in the list are 1/2, then the median is 1/2, which is not less than 1/5. On the other hand, if all the terms are 1/7, then the median is 1/7, which is less than 1/5. Not sufficient.
(2) The product of any two terms of the list is a terminating decimal.
Since the terms in the list are reciprocals of prime numbers, the product of any two terms will be a reduced fraction \(\frac{1}{p*q}\), where \(p\) and \(q\) are prime numbers. For a reduced fraction, in its decimal form, to have a finite number of digits after the decimal point, it must have only 2's and/or 5's in its denominator. Therefore, the list can only consist of 1/2's, 1/5's, or a combination of 1/2's and 1/5's. It cannot include the reciprocal of any other prime, such as 1/3, because no pair with 1/3 will produce a product that is a terminating decimal.
If the two middle terms are both 1/2, then the median is 1/2, which is NOT less than 1/5.
If the two middle terms are both 1/5, then the median is 1/5, which is NOT less than 1/5.
Finally, if the two middle terms are 1/5 and 1/2, then the median is (1/5 + 1/2)/2 = 7/20, which is also NOT less than 1/5.
Since none of the possible medians are less than 1/5, the answer to the question is no. Therefore, statement (2) alone is sufficient to answer the question.
Answer: B
General Discussion
24 Nov 2014, 09:19
Kudos
Bookmarks
Bunuel
Set A consist of 10 terms, each of which is a reciprocal of a prime number, is the median of the set less than 1/5?
(1) Reciprocal of the median is a prime number.
(2) The product of any two terms of the set is a terminating decimal.
(1) Reciprocal of the median is a prime number.
(2) The product of any two terms of the set is a terminating decimal.
Hi again Bunuel!
This is how I am interpreting this question. Based on this interpretation when I read your explanation, I'm getting totally lost. Please help.
Prompt: A set consists of reciprocals of 10 different prime numbers (1/2, 1/3 ..... 1/101....). Is the sum of the 5 and 6th term less than 1.5?
Statement 1: Reciprocal of the average of the 5th and 6th term is also a prime number. I understand your explanation and this is clearly not sufficient.
Statement 2: 1/2 and 1/5 are the only numbers which are a part of this set (squares or cubes of these numbers also can't be a part of this set as the question states that the numbers are reciprocals of primes only). The 10 numbers could be 9 1/2's and 1 1/5 as well. So we don't know have sufficiency?
Is this understanding correct? IMHO answer is E
