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 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.
09 Sep 2019, 21:07
Kudos
Bookmarks
D
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:
56% (01:48) correct
44%
(01:51)
wrong
based on 627
sessions
History
Date
Time
Result
Not Attempted Yet
If a and b are both factors of 50, which of the following must be true?
(A) ab≥ 2
(B) a + b≤ 50
(C) ab is a factor of 100.
(D) ab is a factor of 2500.
(E) ab is even.
09 Sep 2019, 21:53
Kudos
Bookmarks
We are informed that a and b are factors of 50. We are to determine which of the answer choices must be true.
factors of 50 are {1,2,5,10,25,50}.
In A, we are given that ab≥2. This is not always true for the situation a=b=1, where ab=1.
In B, a+b≤50. This also not always true for the situation a=25, and b=50, whereby a+b=75.
In C, ab is factor of 100. This not always true for a=10 and b=25, where ab=250.
In E, ab is even. This is not necessary true for a=1, and b=5, where ab=5, which is not even.
In D, ab is a factor of 2500. This always true since taking the highest possible values that a and be can take, a=b=50, and computing ab=2500. In this case 2500 is a factor of 2500. Hence D must be true.
Answer is therefore D.
factors of 50 are {1,2,5,10,25,50}.
In A, we are given that ab≥2. This is not always true for the situation a=b=1, where ab=1.
In B, a+b≤50. This also not always true for the situation a=25, and b=50, whereby a+b=75.
In C, ab is factor of 100. This not always true for a=10 and b=25, where ab=250.
In E, ab is even. This is not necessary true for a=1, and b=5, where ab=5, which is not even.
In D, ab is a factor of 2500. This always true since taking the highest possible values that a and be can take, a=b=50, and computing ab=2500. In this case 2500 is a factor of 2500. Hence D must be true.
Answer is therefore D.
09 Sep 2019, 22:18
Kudos
Bookmarks
50 has total 6 factors – 1, 2, 5, 10, 25 and 50.
Since nothing is mentioned about relationship between ‘a’ and ‘b’ following conditions are possible:
a. a > b
b. a = b
c. a < b
where 1 ≤ a ≤ 50 and 1 ≤ b ≤ 50.
Let’s test by invalidating ‘must be true’ for all possible conditions –
Answer (D).
Since nothing is mentioned about relationship between ‘a’ and ‘b’ following conditions are possible:
a. a > b
b. a = b
c. a < b
where 1 ≤ a ≤ 50 and 1 ≤ b ≤ 50.
Let’s test by invalidating ‘must be true’ for all possible conditions –
Attachment:
File comment: 50 has total 6 factors –
50 has total 6 factors.JPG [ 75.65 KiB | Viewed 10088 times ]
* - Since 2500 has total 15 factors which include all the 6 factors of 50, taking possible extreme values of ‘a’ and ‘b’ is sufficient.50 has total 6 factors.JPG [ 75.65 KiB | Viewed 10088 times ]
Answer (D).
