Set theory/Venn diagram prob
This topic has expert replies
-
- Master | Next Rank: 500 Posts
- Posts: 294
- Joined: Tue Feb 26, 2008 9:05 pm
- Thanked: 13 times
- Followed by:1 members
In a colony of 75 people, it's found that 35 people know only 2 of the three languages (German, Latin & French), While 10 people know all the three languages.If every person of the colony knows either of the 3 languages, then how many people know only one language ?
- Neo2000
- Legendary Member
- Posts: 519
- Joined: Sat Jan 27, 2007 7:56 am
- Location: India
- Thanked: 31 times
10 ppl know all 3 languages
The Red section indicates ppl who know Only 2 languages and it is given that this = 35
The Green section indicates ppl who know only 1 language.
Out of 75 ppl, 10 know all 3 and 35 know 2 which means that 75 - (10+35) = 30 ppl know only 1 language.
The Red section indicates ppl who know Only 2 languages and it is given that this = 35
The Green section indicates ppl who know only 1 language.
Out of 75 ppl, 10 know all 3 and 35 know 2 which means that 75 - (10+35) = 30 ppl know only 1 language.
- Attachments
-
-
- Master | Next Rank: 500 Posts
- Posts: 294
- Joined: Tue Feb 26, 2008 9:05 pm
- Thanked: 13 times
- Followed by:1 members
Nice lucid analysis Neo 2000 !!
My interpretation was wrong, i was taking 35 as intersection pf any two of the languages, i.e I took G and L = 35 and you know all wrong attempts after that !!
Thank you very much.
My interpretation was wrong, i was taking 35 as intersection pf any two of the languages, i.e I took G and L = 35 and you know all wrong attempts after that !!
Thank you very much.
- AleksandrM
- Legendary Member
- Posts: 566
- Joined: Fri Jan 04, 2008 11:01 am
- Location: Philadelphia
- Thanked: 31 times
- GMAT Score:640
You don't really need a venn diagram for this one. If it said that x know german, y know latin, and z know french, and then w know all three, then how many etc etc etc. In this case it is as simple as subtraction. We are not told that there is group a of people that know neither, so we just ignore it. However, we wouldn't ignore the lack of this piece of information on a DS problem.
75 - 35 - 10 = 30.
75 - 35 - 10 = 30.