Last visit was: 17 Jul 2025, 06:13 It is currently 17 Jul 2025, 06:13
Close
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

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Close
Request Expert Reply
Confirm Cancel
User avatar
2013gmat
Joined: 23 Oct 2012
Last visit: 02 Jan 2015
Posts: 35
Own Kudos:
288
 [25]
Given Kudos: 285
Posts: 35
Kudos: 288
 [25]
4
Kudos
Add Kudos
21
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
KarishmaB
Joined: 16 Oct 2010
Last visit: 17 Jul 2025
Posts: 16,111
Own Kudos:
74,364
 [10]
Given Kudos: 475
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,111
Kudos: 74,364
 [10]
8
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
General Discussion
User avatar
2013gmat
Joined: 23 Oct 2012
Last visit: 02 Jan 2015
Posts: 35
Own Kudos:
Given Kudos: 285
Posts: 35
Kudos: 288
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
danzig
Joined: 11 Aug 2012
Last visit: 07 Nov 2014
Posts: 103
Own Kudos:
Given Kudos: 16
Posts: 103
Kudos: 371
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Karishma,

I don't understand this part of your explanation:
"Notice that 5, 7, 11 and 13 are primes and none of their multiples are in either set. So ignore them. We just need to focus on 2 and 3 of set A and 2, 4 and 6 of set B."

Why do we have to do that? Thanks!
User avatar
KarishmaB
Joined: 16 Oct 2010
Last visit: 17 Jul 2025
Posts: 16,111
Own Kudos:
74,364
 [1]
Given Kudos: 475
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,111
Kudos: 74,364
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
danzig
Karishma,

I don't understand this part of your explanation:
"Notice that 5, 7, 11 and 13 are primes and none of their multiples are in either set. So ignore them. We just need to focus on 2 and 3 of set A and 2, 4 and 6 of set B."

Why do we have to do that? Thanks!

This is part of your step 2: Remove the products that appear more than once.
The logic here is that a product involving 5/7/11/13 will not appear more than once. So we ignore these numbers.

Say we select 5 from A. Now, when we select any number from set B, we get a distinct product i.e. we get 4 distinct products (5*2, 5*4, 5*6, 5*13)
Now think, can you select a number other than 5 from set A and some number from set B to make one of these 4 products? i.e. Without selecting 5 from set A, can you make a product of 10 or 20 or 30 or 65? No, because to make 10/20/30/65, you need a 5 but you have no other 5 or multiple of 5.
Same is the case with 7, 11 and 13 (primes that appear only once in one set). So the products made by these prime numbers will not appear more than once.

You don't really need to think all this during your test. Lots of practice and thorough analysis will make these things intuitive.
User avatar
mau5
User avatar
Verbal Forum Moderator
Joined: 10 Oct 2012
Last visit: 31 Dec 2024
Posts: 479
Own Kudos:
3,279
 [2]
Given Kudos: 141
Posts: 479
Kudos: 3,279
 [2]
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
By looking at Set A, we can see that it's all primes. Thus, we should immediately break down the elements in Set B to their prime factors. That gives :

Set A = {2,3,5,7,11}

Set B = {2, 2x2, 3x2, 13}

Apart from 2x3x2 (taking 2 from set A) which is the same as 3x2x2(taking 3 from set A); there is nothing which can be repeated. Thus, the total unique product = 20-1 = 19.
User avatar
KanishkM
Joined: 09 Mar 2018
Last visit: 18 Dec 2021
Posts: 765
Own Kudos:
Given Kudos: 123
Location: India
Posts: 765
Kudos: 493
Kudos
Add Kudos
Bookmarks
Bookmark this Post
2013gmat
A = {2, 3, 5, 7, 11}
B = {2, 4, 6, 13}

Two integers will be randomly selected from sets A and B, one integer from set A and one from set B, and then multiplied together. How many different products can be obtained?

A. 15
B. 16
C. 19
D. 20
E. 36

Total values will be \(5C_1 * 4C_1\)

But there will one repetitive value as 12

20 - 1

19
User avatar
Kinshook
User avatar
Major Poster
Joined: 03 Jun 2019
Last visit: 16 Jul 2025
Posts: 5,703
Own Kudos:
Given Kudos: 161
Location: India
GMAT 1: 690 Q50 V34
WE:Engineering (Transportation)
Products:
GMAT 1: 690 Q50 V34
Posts: 5,703
Kudos: 5,228
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Given:
A = {2, 3, 5, 7, 11}
B = {2, 4, 6, 13}

Two integers will be randomly selected from sets A and B, one integer from set A and one from set B, and then multiplied together.

Asked: How many different products can be obtained?

A*B = {4,6,8,10,12,14,18,20,22,26,28,30,39,42,44,65,66,91,143} : 19 different products

IMO C
User avatar
Archit3110
User avatar
Major Poster
Joined: 18 Aug 2017
Last visit: 17 July 2025
Posts: 8,350
Own Kudos:
4,830
 [1]
Given Kudos: 243
Status:You learn more from failure than from success.
Location: India
Concentration: Sustainability, Marketing
GMAT Focus 1: 545 Q79 V79 DI73
GPA: 4
WE:Marketing (Energy)
GMAT Focus 1: 545 Q79 V79 DI73
Posts: 8,350
Kudos: 4,830
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Total possible pairs 5c1*4c1= 20
Common values which 2×6 & 3x4
Remove 1 as 12 comes twice
20-1;19
Option C


2013gmat
A = {2, 3, 5, 7, 11}
B = {2, 4, 6, 13}

Two integers will be randomly selected from sets A and B, one integer from set A and one from set B, and then multiplied together. How many different products can be obtained?

A. 15
B. 16
C. 19
D. 20
E. 36

Posted from my mobile device
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 37,434
Own Kudos:
Posts: 37,434
Kudos: 1,013
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Moderators:
Math Expert
102601 posts
PS Forum Moderator
697 posts