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.
Apr 2512:30 AM EDT
-01:30 AM EDT
At one point, she believed GMAT wasn’t for her. After scoring 595, self-doubt crept in and she questioned her potential. But instead of quitting, she made the right strategic changes. The result? A remarkable comeback to 695. Check out how Saakshi did it.
Apr 2601:30 AM EDT
-02:30 AM EDT
Learn how Keshav, a Chartered Accountant, scored an impressive 705 on GMAT in just 30 days with GMATWhiz's expert guidance. In this video, he shares preparation tips and strategies that worked for him, including the mock, time management, and more.
Apr 2610:00 AM EDT
-11:00 AM EDT
The Target Test Prep course represents a quantum leap forward in GMAT preparation, a radical reinterpretation of the way that students should study. Try before you buy with a 5-day, full-access trial of the course for FREE!
Apr 2711:00 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
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
May 0111:00 AM PDT
-12:00 PM PDT
Free- full-length test + 15 concept videos + 150+ short videos + study plan!
Updated on: 05 Feb 2018, 07:11
Originally posted by GMATinsight on 05 Feb 2018, 03:44.
Last edited by GMATinsight on 05 Feb 2018, 07:11, edited 3 times in total.
Last edited by GMATinsight on 05 Feb 2018, 07:11, edited 3 times in total.
Kudos
Bookmarks
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
65%
(hard)
Question Stats:
47% (01:42) correct
53%
(02:00)
wrong
based on 74
sessions
History
Date
Time
Result
Not Attempted Yet
Is Integer x divisible by 25?
(1) \(x^2\) is a multiple of 50
(2) \(x^3\) is a multiple of 625
Source: https://www.GMATinsight.com
(1) \(x^2\) is a multiple of 50
(2) \(x^3\) is a multiple of 625
Source: https://www.GMATinsight.com
05 Feb 2018, 05:59
Kudos
Bookmarks
Answer c
1) let us assume x as 10
10^2=100 which is multiple of 50. But x which is 10 is not divisible by 25
2) let us assume x as 5
5^3=625
Again 5 is not divisible by 25
Together least value should be 1250, which is divisible by 25...
Sent from my Redmi Note 3 using GMAT Club Forum mobile app
1) let us assume x as 10
10^2=100 which is multiple of 50. But x which is 10 is not divisible by 25
2) let us assume x as 5
5^3=625
Again 5 is not divisible by 25
Together least value should be 1250, which is divisible by 25...
Sent from my Redmi Note 3 using GMAT Club Forum mobile app
05 Feb 2018, 08:13
Kudos
Bookmarks
GMATinsight
If x is an integer, then its square and cube will also be integers.
(1) x^2 is a multiple of 50. Now 50 = 2 * 5^2
This tells us that prime factorisation of x^2 has at least one 2 and at least two 5's.
If x^2 has at least two 5's, then x will have at least one 5. So x will be divisible by 5, but we cannot be sure if it will be divisible by 25.
Eg., if x^2 = 100, then x = 10, not divisible by 25. But if x^2 = 2500, then x = 50, which is divisible by 25.
So not sufficient.
(2) x^3 is a multiple of 625. Now 625 = 5^4
So this tells us that cube of x has at least four 5's. So x also must have '5' in its prime factorisation.
But if x has only one 5 in its prime factorisation, then its cube will have only three 5's, and this given condition will not be satisfied. Case rejected
Only if x has at least two 5's in its prime factorisation, will then its cube have at least six 5's, and then only will its cube be divisible by 625.
This tells us that x must have at least two 5's in its prime factorisation, making it divisible by 25. So sufficient.
Hence B answer
