Last visit was: 25 Apr 2024, 12:38 It is currently 25 Apr 2024, 12:38

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
SORT BY:
Date
User avatar
Intern
Intern
Joined: 04 Feb 2011
Posts: 36
Own Kudos [?]: 827 [19]
Given Kudos: 42
Location: US
Send PM
User avatar
Senior Manager
Senior Manager
Joined: 03 Feb 2011
Status:Impossible is not a fact. It's an opinion. It's a dare. Impossible is nothing.
Affiliations: University of Chicago Booth School of Business
Posts: 472
Own Kudos [?]: 892 [0]
Given Kudos: 123
Send PM
Math Expert
Joined: 02 Sep 2009
Posts: 92915
Own Kudos [?]: 619005 [3]
Given Kudos: 81595
Send PM
avatar
Intern
Intern
Joined: 17 Dec 2012
Posts: 3
Own Kudos [?]: 5 [2]
Given Kudos: 2
Send PM
Re: p/s sets [#permalink]
2
Kudos
simple question, but let's solve it in a GMAT way - with out writing any numbers/sets down

Given,
R is set of positive ODD integers < 50
S is set of squares of integers in R

now, we know that all numbers in R are ODD. square of an ODD number is ODD. the qtn is what are the ODD and PERFECT squares < 50. 1, 3,25, and 49...i hope you got what i mean and why i solved this in this way. This is a simple question but solving this question in this way would help us solve 700+ level questions.
User avatar
Manager
Manager
Joined: 24 Jan 2013
Posts: 62
Own Kudos [?]: 372 [0]
Given Kudos: 6
Send PM
Re: R is the set of positive odd integers less than 50, and S is [#permalink]
R is the set of positive odd integers less than 50, and S is the set of the squares of the integers in R.
How many elements does the intersection of R and S contain?

R=1,3,5,7,9,11,13,15...

S=1,9,25,49,81...

Numbers: 1, 9, 25, and 49 are odd integers (less than 50) that are in both sets.

Solution: Four

Answer: C
Senior Manager
Senior Manager
Joined: 04 Jun 2016
Posts: 484
Own Kudos [?]: 2335 [0]
Given Kudos: 36
GMAT 1: 750 Q49 V43
Send PM
Re: R is the set of positive odd integers less than 50, and S is [#permalink]
Lolaergasheva wrote:
R is the set of positive odd integers less than 50, and S is the set of the squares of the integers in R. How many elements does the intersection of R and S contain ?

(A) None
(B) Two
(C) Four
(D) Five
(E) Seven


R={1,3,5,7,9,11,13,15,17,19,21,..................49}
S={1,4,9,16,25,36,49................ 2401}

Common will only be
\(1^2=1\)
\(3^2=9\)
\(5^2=25\)
\(7^2=49\)

so four elements are common in both set

ANSWER IS C
Target Test Prep Representative
Joined: 04 Mar 2011
Status:Head GMAT Instructor
Affiliations: Target Test Prep
Posts: 3043
Own Kudos [?]: 6275 [0]
Given Kudos: 1646
Send PM
Re: R is the set of positive odd integers less than 50, and S is [#permalink]
Expert Reply
Lolaergasheva wrote:
R is the set of positive odd integers less than 50, and S is the set of the squares of the integers in R. How many elements does the intersection of R and S contain ?

(A) None
(B) Two
(C) Four
(D) Five
(E) Seven


Since the a number’s square grows much faster than the number itself, let’s look at the odd perfect squares in S:

1^2 = 1, 3^2 = 9, 5^2 = 25, 7^2 = 49, 9^2 = 81, etc.

We see that, of the numbers in S, 1, 9, 25 and 49 are also in R, so R and S have 4 numbers in common.

Answer: C
Manager
Manager
Joined: 21 Aug 2019
Posts: 105
Own Kudos [?]: 42 [0]
Given Kudos: 353
Send PM
Re: R is the set of positive odd integers less than 50, and S is [#permalink]
Bunuel wrote:
gmat1220 wrote:
squares < 50 {1,4,9,16,25,36,49 }
S = {1,9,25,49}
R = {1,3,.....49}
Hence C.

Lolaergasheva wrote:
R is the set of positive odd integers less than 50, and S is the set of the squares of the integers in R. How many elements does the intersection of R and S contain ?
(A) None
(B) Two
(C) Four
(D) Five
(E) Seven


R is the set of positive odd integers less than 50: R={1, 3, 5, ..., 49}
S is the set of the squares of the integers in R: S={1^2, 3^2, 5^2, ..., 49^2}={1, 9, 25, 49, 81, 121, ..., 2401}

The intersection of R and S contains the odd perfect squares which are less than 50: 1^2=1, 3^2=29, 5^2=25, and 7^2=49.

Answer: C.


Hi Bunuel,

I think there is the typing mistake in the square of 3
GMAT Club Legend
GMAT Club Legend
Joined: 12 Sep 2015
Posts: 6820
Own Kudos [?]: 29929 [1]
Given Kudos: 799
Location: Canada
Send PM
Re: R is the set of positive odd integers less than 50, and S is [#permalink]
1
Kudos
Expert Reply
Top Contributor
Lolaergasheva wrote:
R is the set of positive odd integers less than 50, and S is the set of the squares of the integers in R. How many elements does the intersection of R and S contain ?

(A) None
(B) Two
(C) Four
(D) Five
(E) Seven



So, we need to count all values that satisfy both conditions
In other words, we need to count all values that are BOTH odd integers less than 50 AND are squares of integers

Let's list possible values:
1² = 1 1 is less than 50....keep]
3² = 9 [9 is less than 50....keep]
5² = 25 [25 is less than 50....keep]
7² = 49 [49 is less than 50....keep]
9² = 81 [81 is NOT less than 50.... DON'T keep]

So, the values that satisfy both conditions are: 1, 9, 25, 49
Answer: C

Cheers,
Brent
User avatar
Non-Human User
Joined: 09 Sep 2013
Posts: 32677
Own Kudos [?]: 822 [0]
Given Kudos: 0
Send PM
Re: R is the set of positive odd integers less than 50, and S is [#permalink]
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.
GMAT Club Bot
Re: R is the set of positive odd integers less than 50, and S is [#permalink]
Moderators:
Math Expert
92914 posts
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne