BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Set Theory

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 66
Joined: Sun Jun 29, 2008 8:37 pm
Location: India
Thanked: 1 times

Set Theory

by msd_2008 » Sat Dec 06, 2008 4:48 am
Q. There are 50 students, 22 take accounts, 15 take finance & 14 take marketing. 9 take exactly 2 courses & 1 takes all 3. How many of total took none?

A.10 B.11 C.12 D.14 E.0

OA is A

Regards
MSD
When the going gets tough, the tough gets going.
Top
Source: — Problem Solving |
User avatar
Community Manager
Posts: 1049
Joined: Sun Apr 06, 2008 5:15 pm
Location: Pittsburgh, PA
Thanked: 113 times
Followed by:27 members
GMAT Score:710

by dmateer25 » Sat Dec 06, 2008 5:59 am
I am coming up with B.

What is the source of this question?
Top
Legendary Member
Posts: 833
Joined: Mon Aug 04, 2008 1:56 am
Thanked: 13 times

by vivek.kapoor83 » Sat Dec 06, 2008 6:20 am
True # of objects = (total # in group 1) + (total # in group 2) + (total # in group 3) + (total # in none of the groups) - (# in only groups 1&2) - (# in only groups 1&3) - (# in only groups 2&3) - 2(# in all 3 groups)


...is the formula

acc to ths
50 = 22+15+14 +x-9-2
50 = 51-11+x
50 -40 = x
x=10
IMO A.
Hope it helps.
Top
User avatar
Community Manager
Posts: 1049
Joined: Sun Apr 06, 2008 5:15 pm
Location: Pittsburgh, PA
Thanked: 113 times
Followed by:27 members
GMAT Score:710

by dmateer25 » Sat Dec 06, 2008 6:21 am
vivek.kapoor83 wrote:True # of objects = (total # in group 1) + (total # in group 2) + (total # in group 3) + (total # in none of the groups) - (# in only groups 1&2) - (# in only groups 1&3) - (# in only groups 2&3) - 2(# in all 3 groups)


...is the formula

acc to ths
50 = 22+15+14 +x-9-2
50 = 51-11+x
50 -40 = x
x=10
IMO A.
Hope it helps.
Ah i multiplied by 3 not 2 for the 1 person in all three groups.

Thanks.
Top
Senior | Next Rank: 100 Posts
Posts: 66
Joined: Sun Jun 29, 2008 8:37 pm
Location: India
Thanked: 1 times

by msd_2008 » Sat Dec 06, 2008 5:00 pm
How does this formula apply to AUBUC kind of set questions?
I always thought that the formula for AUBUC = A + B + C - AB - AC - BC + None - All .......note that we are not subtracting 2xAll in this formula.
Is this formula incorrect?

Regards
MSD
When the going gets tough, the tough gets going.
Top
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pm
Thanked: 331 times
Followed by:11 members

by cramya » Sat Dec 06, 2008 5:31 pm
A good one!
Top
Post new topic Post Reply
• Page 1 of 1